From 23dda1b9c64ab1f5a58bc19535792aee05254167 Mon Sep 17 00:00:00 2001
From: Simon Vandel Sillesen <simon.vandel@gmail.com>
Date: Mon, 10 Aug 2020 20:27:41 +0200
Subject: [PATCH] New pass to optimize `if`conditions on integrals to switches
on the integer Fixes #75144
---
src/librustc_middle/mir/interpret/value.rs | 10 +
src/librustc_middle/mir/mod.rs | 13 +
src/librustc_mir/transform/mod.rs | 2 +
.../transform/simplify_comparison_integral.rs | 226 ++++++++++++++++++
src/test/mir-opt/if-condition-int.rs | 65 +++++
...t_opt_bool.SimplifyComparisonIntegral.diff | 30 +++
...opt_floats.SimplifyComparisonIntegral.diff | 37 +++
...comparison.SimplifyComparisonIntegral.diff | 58 +++++
...t.opt_char.SimplifyComparisonIntegral.diff | 39 +++
...int.opt_i8.SimplifyComparisonIntegral.diff | 39 +++
...ltiple_ifs.SimplifyComparisonIntegral.diff | 65 +++++
...t_negative.SimplifyComparisonIntegral.diff | 39 +++
...nt.opt_u32.SimplifyComparisonIntegral.diff | 39 +++
13 files changed, 662 insertions(+)
create mode 100644 src/librustc_mir/transform/simplify_comparison_integral.rs
create mode 100644 src/test/mir-opt/if-condition-int.rs
create mode 100644 src/test/mir-opt/if_condition_int.dont_opt_bool.SimplifyComparisonIntegral.diff
create mode 100644 src/test/mir-opt/if_condition_int.dont_opt_floats.SimplifyComparisonIntegral.diff
create mode 100644 src/test/mir-opt/if_condition_int.dont_remove_comparison.SimplifyComparisonIntegral.diff
create mode 100644 src/test/mir-opt/if_condition_int.opt_char.SimplifyComparisonIntegral.diff
create mode 100644 src/test/mir-opt/if_condition_int.opt_i8.SimplifyComparisonIntegral.diff
create mode 100644 src/test/mir-opt/if_condition_int.opt_multiple_ifs.SimplifyComparisonIntegral.diff
create mode 100644 src/test/mir-opt/if_condition_int.opt_negative.SimplifyComparisonIntegral.diff
create mode 100644 src/test/mir-opt/if_condition_int.opt_u32.SimplifyComparisonIntegral.diff
diff --git a/src/librustc_middle/mir/interpret/value.rs b/src/librustc_middle/mir/interpret/value.rs
index 4c47f25105d..7d6ff3eb5c1 100644
--- a/src/librustc_middle/mir/interpret/value.rs
+++ b/src/librustc_middle/mir/interpret/value.rs
@@ -503,6 +503,11 @@ impl<'tcx, Tag> Scalar<Tag> {
self.to_unsigned_with_bit_width(64).map(|v| u64::try_from(v).unwrap())
}
+ /// Converts the scalar to produce an `u128`. Fails if the scalar is a pointer.
+ pub fn to_u128(self) -> InterpResult<'static, u128> {
+ self.to_unsigned_with_bit_width(128)
+ }
+
pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'static, u64> {
let b = self.to_bits(cx.data_layout().pointer_size)?;
Ok(u64::try_from(b).unwrap())
@@ -535,6 +540,11 @@ impl<'tcx, Tag> Scalar<Tag> {
self.to_signed_with_bit_width(64).map(|v| i64::try_from(v).unwrap())
}
+ /// Converts the scalar to produce an `i128`. Fails if the scalar is a pointer.
+ pub fn to_i128(self) -> InterpResult<'static, i128> {
+ self.to_signed_with_bit_width(128)
+ }
+
pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'static, i64> {
let sz = cx.data_layout().pointer_size;
let b = self.to_bits(sz)?;
diff --git a/src/librustc_middle/mir/mod.rs b/src/librustc_middle/mir/mod.rs
index 7ac7d9b23f1..785a7f0c51a 100644
--- a/src/librustc_middle/mir/mod.rs
+++ b/src/librustc_middle/mir/mod.rs
@@ -1430,6 +1430,15 @@ pub enum StatementKind<'tcx> {
Nop,
}
+impl<'tcx> StatementKind<'tcx> {
+ pub fn as_assign_mut(&mut self) -> Option<&mut Box<(Place<'tcx>, Rvalue<'tcx>)>> {
+ match self {
+ StatementKind::Assign(x) => Some(x),
+ _ => None,
+ }
+ }
+}
+
/// Describes what kind of retag is to be performed.
#[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, PartialEq, Eq, HashStable)]
pub enum RetagKind {
@@ -1843,6 +1852,10 @@ impl<'tcx> Operand<'tcx> {
})
}
+ pub fn is_move(&self) -> bool {
+ matches!(self, Operand::Move(..))
+ }
+
/// Convenience helper to make a literal-like constant from a given scalar value.
/// Since this is used to synthesize MIR, assumes `user_ty` is None.
pub fn const_from_scalar(
diff --git a/src/librustc_mir/transform/mod.rs b/src/librustc_mir/transform/mod.rs
index 0db5bd662ca..c3a34756122 100644
--- a/src/librustc_mir/transform/mod.rs
+++ b/src/librustc_mir/transform/mod.rs
@@ -39,6 +39,7 @@ pub mod required_consts;
pub mod rustc_peek;
pub mod simplify;
pub mod simplify_branches;
+pub mod simplify_comparison_integral;
pub mod simplify_try;
pub mod uninhabited_enum_branching;
pub mod unreachable_prop;
@@ -456,6 +457,7 @@ fn run_optimization_passes<'tcx>(
&match_branches::MatchBranchSimplification,
&const_prop::ConstProp,
&simplify_branches::SimplifyBranches::new("after-const-prop"),
+ &simplify_comparison_integral::SimplifyComparisonIntegral,
&simplify_try::SimplifyArmIdentity,
&simplify_try::SimplifyBranchSame,
©_prop::CopyPropagation,
diff --git a/src/librustc_mir/transform/simplify_comparison_integral.rs b/src/librustc_mir/transform/simplify_comparison_integral.rs
new file mode 100644
index 00000000000..a450a75d091
--- /dev/null
+++ b/src/librustc_mir/transform/simplify_comparison_integral.rs
@@ -0,0 +1,226 @@
+use super::{MirPass, MirSource};
+use rustc_middle::{
+ mir::{
+ interpret::Scalar, BasicBlock, BinOp, Body, Operand, Place, Rvalue, Statement,
+ StatementKind, TerminatorKind,
+ },
+ ty::{Ty, TyCtxt},
+};
+
+/// Pass to convert `if` conditions on integrals into switches on the integral.
+/// For an example, it turns something like
+///
+/// ```
+/// _3 = Eq(move _4, const 43i32);
+/// StorageDead(_4);
+/// switchInt(_3) -> [false: bb2, otherwise: bb3];
+/// ```
+///
+/// into:
+///
+/// ```
+/// switchInt(_4) -> [43i32: bb3, otherwise: bb2];
+/// ```
+pub struct SimplifyComparisonIntegral;
+
+impl<'tcx> MirPass<'tcx> for SimplifyComparisonIntegral {
+ fn run_pass(&self, _: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut Body<'tcx>) {
+ trace!("Running SimplifyComparisonIntegral on {:?}", source);
+
+ let helper = OptimizationFinder { body };
+ let opts = helper.find_optimizations();
+ let mut storage_deads_to_insert = vec![];
+ let mut storage_deads_to_remove: Vec<(usize, BasicBlock)> = vec![];
+ for opt in opts {
+ trace!("SUCCESS: Applying {:?}", opt);
+ // replace terminator with a switchInt that switches on the integer directly
+ let bbs = &mut body.basic_blocks_mut();
+ let bb = &mut bbs[opt.bb_idx];
+ // We only use the bits for the untyped, not length checked `values` field. Thus we are
+ // not using any of the convenience wrappers here and directly access the bits.
+ let new_value = match opt.branch_value_scalar {
+ Scalar::Raw { data, .. } => data,
+ Scalar::Ptr(_) => continue,
+ };
+ const FALSE: u128 = 0;
+ let mut new_targets = opt.targets.clone();
+ let first_is_false_target = opt.values[0] == FALSE;
+ match opt.op {
+ BinOp::Eq => {
+ // if the assignment was Eq we want the true case to be first
+ if first_is_false_target {
+ new_targets.swap(0, 1);
+ }
+ }
+ BinOp::Ne => {
+ // if the assignment was Ne we want the false case to be first
+ if !first_is_false_target {
+ new_targets.swap(0, 1);
+ }
+ }
+ _ => unreachable!(),
+ }
+
+ let terminator = bb.terminator_mut();
+
+ // add StorageDead for the place switched on at the top of each target
+ for bb_idx in new_targets.iter() {
+ storage_deads_to_insert.push((
+ *bb_idx,
+ Statement {
+ source_info: terminator.source_info,
+ kind: StatementKind::StorageDead(opt.to_switch_on.local),
+ },
+ ));
+ }
+
+ terminator.kind = TerminatorKind::SwitchInt {
+ discr: Operand::Move(opt.to_switch_on),
+ switch_ty: opt.branch_value_ty,
+ values: vec![new_value].into(),
+ targets: new_targets,
+ };
+
+ // delete comparison statement if it the value being switched on was moved, which means it can not be user later on
+ if opt.can_remove_bin_op_stmt {
+ bb.statements[opt.bin_op_stmt_idx].make_nop();
+ } else {
+ // if the integer being compared to a const integral is being moved into the comparison,
+ // e.g `_2 = Eq(move _3, const 'x');`
+ // we want to avoid making a double move later on in the switchInt on _3.
+ // So to avoid `switchInt(move _3) -> ['x': bb2, otherwise: bb1];`,
+ // we convert the move in the comparison statement to a copy.
+
+ // unwrap is safe as we know this statement is an assign
+ let box (_, rhs) = bb.statements[opt.bin_op_stmt_idx].kind.as_assign_mut().unwrap();
+
+ use Operand::*;
+ match rhs {
+ Rvalue::BinaryOp(_, ref mut left @ Move(_), Constant(_)) => {
+ *left = Copy(opt.to_switch_on);
+ }
+ Rvalue::BinaryOp(_, Constant(_), ref mut right @ Move(_)) => {
+ *right = Copy(opt.to_switch_on);
+ }
+ _ => (),
+ }
+ }
+
+ // remove StorageDead (if it exists) being used in the assign of the comparison
+ for (stmt_idx, stmt) in bb.statements.iter().enumerate() {
+ if !matches!(stmt.kind, StatementKind::StorageDead(local) if local == opt.to_switch_on.local)
+ {
+ continue;
+ }
+ storage_deads_to_remove.push((stmt_idx, opt.bb_idx))
+ }
+ }
+
+ for (idx, bb_idx) in storage_deads_to_remove {
+ body.basic_blocks_mut()[bb_idx].statements[idx].make_nop();
+ }
+
+ for (idx, stmt) in storage_deads_to_insert {
+ body.basic_blocks_mut()[idx].statements.insert(0, stmt);
+ }
+ }
+}
+
+struct OptimizationFinder<'a, 'tcx> {
+ body: &'a Body<'tcx>,
+}
+
+impl<'a, 'tcx> OptimizationFinder<'a, 'tcx> {
+ fn find_optimizations(&self) -> Vec<OptimizationInfo<'tcx>> {
+ self.body
+ .basic_blocks()
+ .iter_enumerated()
+ .filter_map(|(bb_idx, bb)| {
+ // find switch
+ let (place_switched_on, values, targets, place_switched_on_moved) = match &bb
+ .terminator()
+ .kind
+ {
+ rustc_middle::mir::TerminatorKind::SwitchInt {
+ discr, values, targets, ..
+ } => Some((discr.place()?, values, targets, discr.is_move())),
+ _ => None,
+ }?;
+
+ // find the statement that assigns the place being switched on
+ bb.statements.iter().enumerate().rev().find_map(|(stmt_idx, stmt)| {
+ match &stmt.kind {
+ rustc_middle::mir::StatementKind::Assign(box (lhs, rhs))
+ if *lhs == place_switched_on =>
+ {
+ match rhs {
+ Rvalue::BinaryOp(op @ (BinOp::Eq | BinOp::Ne), left, right) => {
+ let (branch_value_scalar, branch_value_ty, to_switch_on) =
+ find_branch_value_info(left, right)?;
+
+ Some(OptimizationInfo {
+ bin_op_stmt_idx: stmt_idx,
+ bb_idx,
+ can_remove_bin_op_stmt: place_switched_on_moved,
+ to_switch_on,
+ branch_value_scalar,
+ branch_value_ty,
+ op: *op,
+ values: values.clone().into_owned(),
+ targets: targets.clone(),
+ })
+ }
+ _ => None,
+ }
+ }
+ _ => None,
+ }
+ })
+ })
+ .collect()
+ }
+}
+
+fn find_branch_value_info<'tcx>(
+ left: &Operand<'tcx>,
+ right: &Operand<'tcx>,
+) -> Option<(Scalar, Ty<'tcx>, Place<'tcx>)> {
+ // check that either left or right is a constant.
+ // if any are, we can use the other to switch on, and the constant as a value in a switch
+ use Operand::*;
+ match (left, right) {
+ (Constant(branch_value), Copy(to_switch_on) | Move(to_switch_on))
+ | (Copy(to_switch_on) | Move(to_switch_on), Constant(branch_value)) => {
+ let branch_value_ty = branch_value.literal.ty;
+ // we only want to apply this optimization if we are matching on integrals (and chars), as it is not possible to switch on floats
+ if !branch_value_ty.is_integral() && !branch_value_ty.is_char() {
+ return None;
+ };
+ let branch_value_scalar = branch_value.literal.val.try_to_scalar()?;
+ Some((branch_value_scalar, branch_value_ty, *to_switch_on))
+ }
+ _ => None,
+ }
+}
+
+#[derive(Debug)]
+struct OptimizationInfo<'tcx> {
+ /// Basic block to apply the optimization
+ bb_idx: BasicBlock,
+ /// Statement index of Eq/Ne assignment that can be removed. None if the assignment can not be removed - i.e the statement is used later on
+ bin_op_stmt_idx: usize,
+ /// Can remove Eq/Ne assignment
+ can_remove_bin_op_stmt: bool,
+ /// Place that needs to be switched on. This place is of type integral
+ to_switch_on: Place<'tcx>,
+ /// Constant to use in switch target value
+ branch_value_scalar: Scalar,
+ /// Type of the constant value
+ branch_value_ty: Ty<'tcx>,
+ /// Either Eq or Ne
+ op: BinOp,
+ /// Current values used in the switch target. This needs to be replaced with the branch_value
+ values: Vec<u128>,
+ /// Current targets used in the switch
+ targets: Vec<BasicBlock>,
+}
diff --git a/src/test/mir-opt/if-condition-int.rs b/src/test/mir-opt/if-condition-int.rs
new file mode 100644
index 00000000000..b34389a0ab5
--- /dev/null
+++ b/src/test/mir-opt/if-condition-int.rs
@@ -0,0 +1,65 @@
+// compile-flags: -O
+// EMIT_MIR if_condition_int.opt_u32.SimplifyComparisonIntegral.diff
+// EMIT_MIR if_condition_int.opt_negative.SimplifyComparisonIntegral.diff
+// EMIT_MIR if_condition_int.opt_char.SimplifyComparisonIntegral.diff
+// EMIT_MIR if_condition_int.opt_i8.SimplifyComparisonIntegral.diff
+// EMIT_MIR if_condition_int.dont_opt_bool.SimplifyComparisonIntegral.diff
+// EMIT_MIR if_condition_int.opt_multiple_ifs.SimplifyComparisonIntegral.diff
+// EMIT_MIR if_condition_int.dont_remove_comparison.SimplifyComparisonIntegral.diff
+// EMIT_MIR if_condition_int.dont_opt_floats.SimplifyComparisonIntegral.diff
+
+fn opt_u32(x: u32) -> u32 {
+ if x == 42 { 0 } else { 1 }
+}
+
+// don't opt: it is already optimal to switch on the bool
+fn dont_opt_bool(x: bool) -> u32 {
+ if x { 0 } else { 1 }
+}
+
+fn opt_char(x: char) -> u32 {
+ if x == 'x' { 0 } else { 1 }
+}
+
+fn opt_i8(x: i8) -> u32 {
+ if x == 42 { 0 } else { 1 }
+}
+
+fn opt_negative(x: i32) -> u32 {
+ if x == -42 { 0 } else { 1 }
+}
+
+fn opt_multiple_ifs(x: u32) -> u32 {
+ if x == 42 {
+ 0
+ } else if x != 21 {
+ 1
+ } else {
+ 2
+ }
+}
+
+// test that we optimize, but do not remove the b statement, as that is used later on
+fn dont_remove_comparison(a: i8) -> i32 {
+ let b = a == 17;
+ match b {
+ false => 10 + b as i32,
+ true => 100 + b as i32,
+ }
+}
+
+// test that we do not optimize on floats
+fn dont_opt_floats(a: f32) -> i32 {
+ if a == -42.0 { 0 } else { 1 }
+}
+
+fn main() {
+ opt_u32(0);
+ opt_char('0');
+ opt_i8(22);
+ dont_opt_bool(false);
+ opt_negative(0);
+ opt_multiple_ifs(0);
+ dont_remove_comparison(11);
+ dont_opt_floats(1.0);
+}
diff --git a/src/test/mir-opt/if_condition_int.dont_opt_bool.SimplifyComparisonIntegral.diff b/src/test/mir-opt/if_condition_int.dont_opt_bool.SimplifyComparisonIntegral.diff
new file mode 100644
index 00000000000..993ff660caa
--- /dev/null
+++ b/src/test/mir-opt/if_condition_int.dont_opt_bool.SimplifyComparisonIntegral.diff
@@ -0,0 +1,30 @@
+- // MIR for `dont_opt_bool` before SimplifyComparisonIntegral
++ // MIR for `dont_opt_bool` after SimplifyComparisonIntegral
+
+ fn dont_opt_bool(_1: bool) -> u32 {
+ debug x => _1; // in scope 0 at $DIR/if-condition-int.rs:16:18: 16:19
+ let mut _0: u32; // return place in scope 0 at $DIR/if-condition-int.rs:16:30: 16:33
+ let mut _2: bool; // in scope 0 at $DIR/if-condition-int.rs:17:8: 17:9
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/if-condition-int.rs:17:8: 17:9
+ _2 = _1; // scope 0 at $DIR/if-condition-int.rs:17:8: 17:9
+ switchInt(_2) -> [false: bb1, otherwise: bb2]; // scope 0 at $DIR/if-condition-int.rs:17:5: 17:26
+ }
+
+ bb1: {
+ _0 = const 1_u32; // scope 0 at $DIR/if-condition-int.rs:17:23: 17:24
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:17:5: 17:26
+ }
+
+ bb2: {
+ _0 = const 0_u32; // scope 0 at $DIR/if-condition-int.rs:17:12: 17:13
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:17:5: 17:26
+ }
+
+ bb3: {
+ StorageDead(_2); // scope 0 at $DIR/if-condition-int.rs:18:1: 18:2
+ return; // scope 0 at $DIR/if-condition-int.rs:18:2: 18:2
+ }
+ }
+
diff --git a/src/test/mir-opt/if_condition_int.dont_opt_floats.SimplifyComparisonIntegral.diff b/src/test/mir-opt/if_condition_int.dont_opt_floats.SimplifyComparisonIntegral.diff
new file mode 100644
index 00000000000..8ae9168c950
--- /dev/null
+++ b/src/test/mir-opt/if_condition_int.dont_opt_floats.SimplifyComparisonIntegral.diff
@@ -0,0 +1,37 @@
+- // MIR for `dont_opt_floats` before SimplifyComparisonIntegral
++ // MIR for `dont_opt_floats` after SimplifyComparisonIntegral
+
+ fn dont_opt_floats(_1: f32) -> i32 {
+ debug a => _1; // in scope 0 at $DIR/if-condition-int.rs:52:20: 52:21
+ let mut _0: i32; // return place in scope 0 at $DIR/if-condition-int.rs:52:31: 52:34
+ let mut _2: bool; // in scope 0 at $DIR/if-condition-int.rs:53:8: 53:18
+ let mut _3: f32; // in scope 0 at $DIR/if-condition-int.rs:53:8: 53:9
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/if-condition-int.rs:53:8: 53:18
+ StorageLive(_3); // scope 0 at $DIR/if-condition-int.rs:53:8: 53:9
+ _3 = _1; // scope 0 at $DIR/if-condition-int.rs:53:8: 53:9
+ _2 = Eq(move _3, const -42f32); // scope 0 at $DIR/if-condition-int.rs:53:8: 53:18
+ // mir::Constant
+ // + span: $DIR/if-condition-int.rs:53:13: 53:18
+ // + literal: Const { ty: f32, val: Value(Scalar(0xc2280000)) }
+ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:53:17: 53:18
+ switchInt(_2) -> [false: bb1, otherwise: bb2]; // scope 0 at $DIR/if-condition-int.rs:53:5: 53:35
+ }
+
+ bb1: {
+ _0 = const 1_i32; // scope 0 at $DIR/if-condition-int.rs:53:32: 53:33
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:53:5: 53:35
+ }
+
+ bb2: {
+ _0 = const 0_i32; // scope 0 at $DIR/if-condition-int.rs:53:21: 53:22
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:53:5: 53:35
+ }
+
+ bb3: {
+ StorageDead(_2); // scope 0 at $DIR/if-condition-int.rs:54:1: 54:2
+ return; // scope 0 at $DIR/if-condition-int.rs:54:2: 54:2
+ }
+ }
+
diff --git a/src/test/mir-opt/if_condition_int.dont_remove_comparison.SimplifyComparisonIntegral.diff b/src/test/mir-opt/if_condition_int.dont_remove_comparison.SimplifyComparisonIntegral.diff
new file mode 100644
index 00000000000..b590be5370f
--- /dev/null
+++ b/src/test/mir-opt/if_condition_int.dont_remove_comparison.SimplifyComparisonIntegral.diff
@@ -0,0 +1,58 @@
+- // MIR for `dont_remove_comparison` before SimplifyComparisonIntegral
++ // MIR for `dont_remove_comparison` after SimplifyComparisonIntegral
+
+ fn dont_remove_comparison(_1: i8) -> i32 {
+ debug a => _1; // in scope 0 at $DIR/if-condition-int.rs:43:27: 43:28
+ let mut _0: i32; // return place in scope 0 at $DIR/if-condition-int.rs:43:37: 43:40
+ let _2: bool; // in scope 0 at $DIR/if-condition-int.rs:44:9: 44:10
+ let mut _3: i8; // in scope 0 at $DIR/if-condition-int.rs:44:13: 44:14
+ let mut _4: i32; // in scope 0 at $DIR/if-condition-int.rs:46:23: 46:31
+ let mut _5: bool; // in scope 0 at $DIR/if-condition-int.rs:46:23: 46:24
+ let mut _6: i32; // in scope 0 at $DIR/if-condition-int.rs:47:23: 47:31
+ let mut _7: bool; // in scope 0 at $DIR/if-condition-int.rs:47:23: 47:24
+ scope 1 {
+ debug b => _2; // in scope 1 at $DIR/if-condition-int.rs:44:9: 44:10
+ }
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/if-condition-int.rs:44:9: 44:10
+ StorageLive(_3); // scope 0 at $DIR/if-condition-int.rs:44:13: 44:14
+ _3 = _1; // scope 0 at $DIR/if-condition-int.rs:44:13: 44:14
+- _2 = Eq(move _3, const 17_i8); // scope 0 at $DIR/if-condition-int.rs:44:13: 44:20
+- StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:44:19: 44:20
+- switchInt(_2) -> [false: bb2, otherwise: bb1]; // scope 1 at $DIR/if-condition-int.rs:46:9: 46:14
++ _2 = Eq(_3, const 17_i8); // scope 0 at $DIR/if-condition-int.rs:44:13: 44:20
++ nop; // scope 0 at $DIR/if-condition-int.rs:44:19: 44:20
++ switchInt(move _3) -> [17_i8: bb1, otherwise: bb2]; // scope 1 at $DIR/if-condition-int.rs:46:9: 46:14
+ }
+
+ bb1: {
++ StorageDead(_3); // scope 1 at $DIR/if-condition-int.rs:46:9: 46:14
+ StorageLive(_6); // scope 1 at $DIR/if-condition-int.rs:47:23: 47:31
+ StorageLive(_7); // scope 1 at $DIR/if-condition-int.rs:47:23: 47:24
+ _7 = _2; // scope 1 at $DIR/if-condition-int.rs:47:23: 47:24
+ _6 = move _7 as i32 (Misc); // scope 1 at $DIR/if-condition-int.rs:47:23: 47:31
+ StorageDead(_7); // scope 1 at $DIR/if-condition-int.rs:47:30: 47:31
+ _0 = Add(const 100_i32, move _6); // scope 1 at $DIR/if-condition-int.rs:47:17: 47:31
+ StorageDead(_6); // scope 1 at $DIR/if-condition-int.rs:47:30: 47:31
+ goto -> bb3; // scope 1 at $DIR/if-condition-int.rs:45:5: 48:6
+ }
+
+ bb2: {
++ StorageDead(_3); // scope 1 at $DIR/if-condition-int.rs:46:9: 46:14
+ StorageLive(_4); // scope 1 at $DIR/if-condition-int.rs:46:23: 46:31
+ StorageLive(_5); // scope 1 at $DIR/if-condition-int.rs:46:23: 46:24
+ _5 = _2; // scope 1 at $DIR/if-condition-int.rs:46:23: 46:24
+ _4 = move _5 as i32 (Misc); // scope 1 at $DIR/if-condition-int.rs:46:23: 46:31
+ StorageDead(_5); // scope 1 at $DIR/if-condition-int.rs:46:30: 46:31
+ _0 = Add(const 10_i32, move _4); // scope 1 at $DIR/if-condition-int.rs:46:18: 46:31
+ StorageDead(_4); // scope 1 at $DIR/if-condition-int.rs:46:30: 46:31
+ goto -> bb3; // scope 1 at $DIR/if-condition-int.rs:45:5: 48:6
+ }
+
+ bb3: {
+ StorageDead(_2); // scope 0 at $DIR/if-condition-int.rs:49:1: 49:2
+ return; // scope 0 at $DIR/if-condition-int.rs:49:2: 49:2
+ }
+ }
+
diff --git a/src/test/mir-opt/if_condition_int.opt_char.SimplifyComparisonIntegral.diff b/src/test/mir-opt/if_condition_int.opt_char.SimplifyComparisonIntegral.diff
new file mode 100644
index 00000000000..ae0960028a8
--- /dev/null
+++ b/src/test/mir-opt/if_condition_int.opt_char.SimplifyComparisonIntegral.diff
@@ -0,0 +1,39 @@
+- // MIR for `opt_char` before SimplifyComparisonIntegral
++ // MIR for `opt_char` after SimplifyComparisonIntegral
+
+ fn opt_char(_1: char) -> u32 {
+ debug x => _1; // in scope 0 at $DIR/if-condition-int.rs:20:13: 20:14
+ let mut _0: u32; // return place in scope 0 at $DIR/if-condition-int.rs:20:25: 20:28
+ let mut _2: bool; // in scope 0 at $DIR/if-condition-int.rs:21:8: 21:16
+ let mut _3: char; // in scope 0 at $DIR/if-condition-int.rs:21:8: 21:9
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/if-condition-int.rs:21:8: 21:16
+ StorageLive(_3); // scope 0 at $DIR/if-condition-int.rs:21:8: 21:9
+ _3 = _1; // scope 0 at $DIR/if-condition-int.rs:21:8: 21:9
+- _2 = Eq(move _3, const 'x'); // scope 0 at $DIR/if-condition-int.rs:21:8: 21:16
+- StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:21:15: 21:16
+- switchInt(_2) -> [false: bb1, otherwise: bb2]; // scope 0 at $DIR/if-condition-int.rs:21:5: 21:33
++ _2 = Eq(_3, const 'x'); // scope 0 at $DIR/if-condition-int.rs:21:8: 21:16
++ nop; // scope 0 at $DIR/if-condition-int.rs:21:15: 21:16
++ switchInt(move _3) -> ['x': bb2, otherwise: bb1]; // scope 0 at $DIR/if-condition-int.rs:21:5: 21:33
+ }
+
+ bb1: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:21:5: 21:33
+ _0 = const 1_u32; // scope 0 at $DIR/if-condition-int.rs:21:30: 21:31
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:21:5: 21:33
+ }
+
+ bb2: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:21:5: 21:33
+ _0 = const 0_u32; // scope 0 at $DIR/if-condition-int.rs:21:19: 21:20
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:21:5: 21:33
+ }
+
+ bb3: {
+ StorageDead(_2); // scope 0 at $DIR/if-condition-int.rs:22:1: 22:2
+ return; // scope 0 at $DIR/if-condition-int.rs:22:2: 22:2
+ }
+ }
+
diff --git a/src/test/mir-opt/if_condition_int.opt_i8.SimplifyComparisonIntegral.diff b/src/test/mir-opt/if_condition_int.opt_i8.SimplifyComparisonIntegral.diff
new file mode 100644
index 00000000000..8d59e51ac2b
--- /dev/null
+++ b/src/test/mir-opt/if_condition_int.opt_i8.SimplifyComparisonIntegral.diff
@@ -0,0 +1,39 @@
+- // MIR for `opt_i8` before SimplifyComparisonIntegral
++ // MIR for `opt_i8` after SimplifyComparisonIntegral
+
+ fn opt_i8(_1: i8) -> u32 {
+ debug x => _1; // in scope 0 at $DIR/if-condition-int.rs:24:11: 24:12
+ let mut _0: u32; // return place in scope 0 at $DIR/if-condition-int.rs:24:21: 24:24
+ let mut _2: bool; // in scope 0 at $DIR/if-condition-int.rs:25:8: 25:15
+ let mut _3: i8; // in scope 0 at $DIR/if-condition-int.rs:25:8: 25:9
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/if-condition-int.rs:25:8: 25:15
+ StorageLive(_3); // scope 0 at $DIR/if-condition-int.rs:25:8: 25:9
+ _3 = _1; // scope 0 at $DIR/if-condition-int.rs:25:8: 25:9
+- _2 = Eq(move _3, const 42_i8); // scope 0 at $DIR/if-condition-int.rs:25:8: 25:15
+- StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:25:14: 25:15
+- switchInt(_2) -> [false: bb1, otherwise: bb2]; // scope 0 at $DIR/if-condition-int.rs:25:5: 25:32
++ _2 = Eq(_3, const 42_i8); // scope 0 at $DIR/if-condition-int.rs:25:8: 25:15
++ nop; // scope 0 at $DIR/if-condition-int.rs:25:14: 25:15
++ switchInt(move _3) -> [42_i8: bb2, otherwise: bb1]; // scope 0 at $DIR/if-condition-int.rs:25:5: 25:32
+ }
+
+ bb1: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:25:5: 25:32
+ _0 = const 1_u32; // scope 0 at $DIR/if-condition-int.rs:25:29: 25:30
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:25:5: 25:32
+ }
+
+ bb2: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:25:5: 25:32
+ _0 = const 0_u32; // scope 0 at $DIR/if-condition-int.rs:25:18: 25:19
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:25:5: 25:32
+ }
+
+ bb3: {
+ StorageDead(_2); // scope 0 at $DIR/if-condition-int.rs:26:1: 26:2
+ return; // scope 0 at $DIR/if-condition-int.rs:26:2: 26:2
+ }
+ }
+
diff --git a/src/test/mir-opt/if_condition_int.opt_multiple_ifs.SimplifyComparisonIntegral.diff b/src/test/mir-opt/if_condition_int.opt_multiple_ifs.SimplifyComparisonIntegral.diff
new file mode 100644
index 00000000000..c4975661efe
--- /dev/null
+++ b/src/test/mir-opt/if_condition_int.opt_multiple_ifs.SimplifyComparisonIntegral.diff
@@ -0,0 +1,65 @@
+- // MIR for `opt_multiple_ifs` before SimplifyComparisonIntegral
++ // MIR for `opt_multiple_ifs` after SimplifyComparisonIntegral
+
+ fn opt_multiple_ifs(_1: u32) -> u32 {
+ debug x => _1; // in scope 0 at $DIR/if-condition-int.rs:32:21: 32:22
+ let mut _0: u32; // return place in scope 0 at $DIR/if-condition-int.rs:32:32: 32:35
+ let mut _2: bool; // in scope 0 at $DIR/if-condition-int.rs:33:8: 33:15
+ let mut _3: u32; // in scope 0 at $DIR/if-condition-int.rs:33:8: 33:9
+ let mut _4: bool; // in scope 0 at $DIR/if-condition-int.rs:35:15: 35:22
+ let mut _5: u32; // in scope 0 at $DIR/if-condition-int.rs:35:15: 35:16
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/if-condition-int.rs:33:8: 33:15
+ StorageLive(_3); // scope 0 at $DIR/if-condition-int.rs:33:8: 33:9
+ _3 = _1; // scope 0 at $DIR/if-condition-int.rs:33:8: 33:9
+- _2 = Eq(move _3, const 42_u32); // scope 0 at $DIR/if-condition-int.rs:33:8: 33:15
+- StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:33:14: 33:15
+- switchInt(_2) -> [false: bb1, otherwise: bb2]; // scope 0 at $DIR/if-condition-int.rs:33:5: 39:6
++ _2 = Eq(_3, const 42_u32); // scope 0 at $DIR/if-condition-int.rs:33:8: 33:15
++ nop; // scope 0 at $DIR/if-condition-int.rs:33:14: 33:15
++ switchInt(move _3) -> [42_u32: bb2, otherwise: bb1]; // scope 0 at $DIR/if-condition-int.rs:33:5: 39:6
+ }
+
+ bb1: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:33:5: 39:6
+ StorageLive(_4); // scope 0 at $DIR/if-condition-int.rs:35:15: 35:22
+ StorageLive(_5); // scope 0 at $DIR/if-condition-int.rs:35:15: 35:16
+ _5 = _1; // scope 0 at $DIR/if-condition-int.rs:35:15: 35:16
+- _4 = Ne(move _5, const 21_u32); // scope 0 at $DIR/if-condition-int.rs:35:15: 35:22
+- StorageDead(_5); // scope 0 at $DIR/if-condition-int.rs:35:21: 35:22
+- switchInt(_4) -> [false: bb3, otherwise: bb4]; // scope 0 at $DIR/if-condition-int.rs:35:12: 39:6
++ _4 = Ne(_5, const 21_u32); // scope 0 at $DIR/if-condition-int.rs:35:15: 35:22
++ nop; // scope 0 at $DIR/if-condition-int.rs:35:21: 35:22
++ switchInt(move _5) -> [21_u32: bb3, otherwise: bb4]; // scope 0 at $DIR/if-condition-int.rs:35:12: 39:6
+ }
+
+ bb2: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:33:5: 39:6
+ _0 = const 0_u32; // scope 0 at $DIR/if-condition-int.rs:34:9: 34:10
+ goto -> bb6; // scope 0 at $DIR/if-condition-int.rs:33:5: 39:6
+ }
+
+ bb3: {
++ StorageDead(_5); // scope 0 at $DIR/if-condition-int.rs:35:12: 39:6
+ _0 = const 2_u32; // scope 0 at $DIR/if-condition-int.rs:38:9: 38:10
+ goto -> bb5; // scope 0 at $DIR/if-condition-int.rs:35:12: 39:6
+ }
+
+ bb4: {
++ StorageDead(_5); // scope 0 at $DIR/if-condition-int.rs:35:12: 39:6
+ _0 = const 1_u32; // scope 0 at $DIR/if-condition-int.rs:36:9: 36:10
+ goto -> bb5; // scope 0 at $DIR/if-condition-int.rs:35:12: 39:6
+ }
+
+ bb5: {
+ StorageDead(_4); // scope 0 at $DIR/if-condition-int.rs:39:5: 39:6
+ goto -> bb6; // scope 0 at $DIR/if-condition-int.rs:33:5: 39:6
+ }
+
+ bb6: {
+ StorageDead(_2); // scope 0 at $DIR/if-condition-int.rs:40:1: 40:2
+ return; // scope 0 at $DIR/if-condition-int.rs:40:2: 40:2
+ }
+ }
+
diff --git a/src/test/mir-opt/if_condition_int.opt_negative.SimplifyComparisonIntegral.diff b/src/test/mir-opt/if_condition_int.opt_negative.SimplifyComparisonIntegral.diff
new file mode 100644
index 00000000000..d7f544e44c0
--- /dev/null
+++ b/src/test/mir-opt/if_condition_int.opt_negative.SimplifyComparisonIntegral.diff
@@ -0,0 +1,39 @@
+- // MIR for `opt_negative` before SimplifyComparisonIntegral
++ // MIR for `opt_negative` after SimplifyComparisonIntegral
+
+ fn opt_negative(_1: i32) -> u32 {
+ debug x => _1; // in scope 0 at $DIR/if-condition-int.rs:28:17: 28:18
+ let mut _0: u32; // return place in scope 0 at $DIR/if-condition-int.rs:28:28: 28:31
+ let mut _2: bool; // in scope 0 at $DIR/if-condition-int.rs:29:8: 29:16
+ let mut _3: i32; // in scope 0 at $DIR/if-condition-int.rs:29:8: 29:9
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/if-condition-int.rs:29:8: 29:16
+ StorageLive(_3); // scope 0 at $DIR/if-condition-int.rs:29:8: 29:9
+ _3 = _1; // scope 0 at $DIR/if-condition-int.rs:29:8: 29:9
+- _2 = Eq(move _3, const -42_i32); // scope 0 at $DIR/if-condition-int.rs:29:8: 29:16
+- StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:29:15: 29:16
+- switchInt(_2) -> [false: bb1, otherwise: bb2]; // scope 0 at $DIR/if-condition-int.rs:29:5: 29:33
++ _2 = Eq(_3, const -42_i32); // scope 0 at $DIR/if-condition-int.rs:29:8: 29:16
++ nop; // scope 0 at $DIR/if-condition-int.rs:29:15: 29:16
++ switchInt(move _3) -> [-42_i32: bb2, otherwise: bb1]; // scope 0 at $DIR/if-condition-int.rs:29:5: 29:33
+ }
+
+ bb1: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:29:5: 29:33
+ _0 = const 1_u32; // scope 0 at $DIR/if-condition-int.rs:29:30: 29:31
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:29:5: 29:33
+ }
+
+ bb2: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:29:5: 29:33
+ _0 = const 0_u32; // scope 0 at $DIR/if-condition-int.rs:29:19: 29:20
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:29:5: 29:33
+ }
+
+ bb3: {
+ StorageDead(_2); // scope 0 at $DIR/if-condition-int.rs:30:1: 30:2
+ return; // scope 0 at $DIR/if-condition-int.rs:30:2: 30:2
+ }
+ }
+
diff --git a/src/test/mir-opt/if_condition_int.opt_u32.SimplifyComparisonIntegral.diff b/src/test/mir-opt/if_condition_int.opt_u32.SimplifyComparisonIntegral.diff
new file mode 100644
index 00000000000..51e00e680c2
--- /dev/null
+++ b/src/test/mir-opt/if_condition_int.opt_u32.SimplifyComparisonIntegral.diff
@@ -0,0 +1,39 @@
+- // MIR for `opt_u32` before SimplifyComparisonIntegral
++ // MIR for `opt_u32` after SimplifyComparisonIntegral
+
+ fn opt_u32(_1: u32) -> u32 {
+ debug x => _1; // in scope 0 at $DIR/if-condition-int.rs:11:12: 11:13
+ let mut _0: u32; // return place in scope 0 at $DIR/if-condition-int.rs:11:23: 11:26
+ let mut _2: bool; // in scope 0 at $DIR/if-condition-int.rs:12:8: 12:15
+ let mut _3: u32; // in scope 0 at $DIR/if-condition-int.rs:12:8: 12:9
+
+ bb0: {
+ StorageLive(_2); // scope 0 at $DIR/if-condition-int.rs:12:8: 12:15
+ StorageLive(_3); // scope 0 at $DIR/if-condition-int.rs:12:8: 12:9
+ _3 = _1; // scope 0 at $DIR/if-condition-int.rs:12:8: 12:9
+- _2 = Eq(move _3, const 42_u32); // scope 0 at $DIR/if-condition-int.rs:12:8: 12:15
+- StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:12:14: 12:15
+- switchInt(_2) -> [false: bb1, otherwise: bb2]; // scope 0 at $DIR/if-condition-int.rs:12:5: 12:32
++ _2 = Eq(_3, const 42_u32); // scope 0 at $DIR/if-condition-int.rs:12:8: 12:15
++ nop; // scope 0 at $DIR/if-condition-int.rs:12:14: 12:15
++ switchInt(move _3) -> [42_u32: bb2, otherwise: bb1]; // scope 0 at $DIR/if-condition-int.rs:12:5: 12:32
+ }
+
+ bb1: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:12:5: 12:32
+ _0 = const 1_u32; // scope 0 at $DIR/if-condition-int.rs:12:29: 12:30
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:12:5: 12:32
+ }
+
+ bb2: {
++ StorageDead(_3); // scope 0 at $DIR/if-condition-int.rs:12:5: 12:32
+ _0 = const 0_u32; // scope 0 at $DIR/if-condition-int.rs:12:18: 12:19
+ goto -> bb3; // scope 0 at $DIR/if-condition-int.rs:12:5: 12:32
+ }
+
+ bb3: {
+ StorageDead(_2); // scope 0 at $DIR/if-condition-int.rs:13:1: 13:2
+ return; // scope 0 at $DIR/if-condition-int.rs:13:2: 13:2
+ }
+ }
+