From 5df2bb1bccd8394dbd73ffa52dea1151dcd0b0ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Steinbrink?= <bsteinbr@gmail.com>
Date: Sat, 13 Jul 2013 04:09:57 +0200
Subject: [PATCH] Avoid empty "static_allocas" blocks
When there are no allocas, we don't need a block for them.
---
src/librustc/middle/trans/base.rs | 37 ++++++++++++++++------------
src/librustc/middle/trans/common.rs | 10 +++++++-
src/librustc/middle/trans/foreign.rs | 2 +-
3 files changed, 31 insertions(+), 18 deletions(-)
diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index bbd676c87b4..1173fa49419 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -1557,7 +1557,7 @@ pub fn alloca_maybe_zeroed(cx: block, ty: Type, name: &str, zero: bool) -> Value
return llvm::LLVMGetUndef(ty.to_ref());
}
}
- let initcx = base::raw_block(cx.fcx, false, cx.fcx.llstaticallocas);
+ let initcx = base::raw_block(cx.fcx, false, cx.fcx.get_llstaticallocas());
let p = Alloca(initcx, ty, name);
if zero { memzero(initcx, p, ty); }
p
@@ -1570,21 +1570,18 @@ pub fn arrayalloca(cx: block, ty: Type, v: ValueRef) -> ValueRef {
return llvm::LLVMGetUndef(ty.to_ref());
}
}
- return ArrayAlloca(base::raw_block(cx.fcx, false, cx.fcx.llstaticallocas), ty, v);
+ return ArrayAlloca(base::raw_block(cx.fcx, false, cx.fcx.get_llstaticallocas()), ty, v);
}
pub struct BasicBlocks {
sa: BasicBlockRef,
}
-// Creates the standard set of basic blocks for a function
-pub fn mk_standard_basic_blocks(llfn: ValueRef) -> BasicBlocks {
+pub fn mk_staticallocas_basic_block(llfn: ValueRef) -> BasicBlockRef {
unsafe {
let cx = task_llcx();
- BasicBlocks {
- sa: str::as_c_str("static_allocas",
- |buf| llvm::LLVMAppendBasicBlockInContext(cx, llfn, buf)),
- }
+ str::as_c_str("static_allocas",
+ |buf| llvm::LLVMAppendBasicBlockInContext(cx, llfn, buf))
}
}
@@ -1604,7 +1601,7 @@ pub fn make_return_pointer(fcx: fn_ctxt, output_type: ty::t) -> ValueRef {
llvm::LLVMGetParam(fcx.llfn, 0)
} else {
let lloutputtype = type_of::type_of(fcx.ccx, output_type);
- alloca(raw_block(fcx, false, fcx.llstaticallocas), lloutputtype,
+ alloca(raw_block(fcx, false, fcx.get_llstaticallocas()), lloutputtype,
"__make_return_pointer")
}
}
@@ -1632,8 +1629,6 @@ pub fn new_fn_ctxt_w_id(ccx: @mut CrateContext,
id,
param_substs.repr(ccx.tcx));
- let llbbs = mk_standard_basic_blocks(llfndecl);
-
let substd_output_type = match param_substs {
None => output_type,
Some(substs) => {
@@ -1647,7 +1642,7 @@ pub fn new_fn_ctxt_w_id(ccx: @mut CrateContext,
llvm::LLVMGetUndef(Type::i8p().to_ref())
},
llretptr: None,
- llstaticallocas: llbbs.sa,
+ llstaticallocas: None,
llloadenv: None,
llreturn: None,
llself: None,
@@ -1821,14 +1816,24 @@ pub fn build_return_block(fcx: fn_ctxt, ret_cx: block) {
pub fn tie_up_header_blocks(fcx: fn_ctxt, lltop: BasicBlockRef) {
let _icx = push_ctxt("tie_up_header_blocks");
- match fcx.llloadenv {
+ let llnext = match fcx.llloadenv {
Some(ll) => {
- Br(raw_block(fcx, false, fcx.llstaticallocas), ll);
+ unsafe {
+ llvm::LLVMMoveBasicBlockBefore(ll, lltop);
+ }
Br(raw_block(fcx, false, ll), lltop);
+ ll
}
- None => {
- Br(raw_block(fcx, false, fcx.llstaticallocas), lltop);
+ None => lltop
+ };
+ match fcx.llstaticallocas {
+ Some(ll) => {
+ unsafe {
+ llvm::LLVMMoveBasicBlockBefore(ll, llnext);
+ }
+ Br(raw_block(fcx, false, ll), llnext);
}
+ None => ()
}
}
diff --git a/src/librustc/middle/trans/common.rs b/src/librustc/middle/trans/common.rs
index 2e016377e75..83029a90260 100644
--- a/src/librustc/middle/trans/common.rs
+++ b/src/librustc/middle/trans/common.rs
@@ -178,7 +178,7 @@ pub struct fn_ctxt_ {
// the function, due to LLVM's quirks.
// A block for all the function's static allocas, so that LLVM
// will coalesce them into a single alloca call.
- llstaticallocas: BasicBlockRef,
+ llstaticallocas: Option<BasicBlockRef>,
// A block containing code that copies incoming arguments to space
// already allocated by code in one of the llallocas blocks.
// (LLVM requires that arguments be copied to local allocas before
@@ -251,6 +251,14 @@ impl fn_ctxt_ {
}
}
+ pub fn get_llstaticallocas(&mut self) -> BasicBlockRef {
+ if self.llstaticallocas.is_none() {
+ self.llstaticallocas = Some(base::mk_staticallocas_basic_block(self.llfn));
+ }
+
+ self.llstaticallocas.get()
+ }
+
pub fn get_llreturn(&mut self) -> BasicBlockRef {
if self.llreturn.is_none() {
self.llreturn = Some(base::mk_return_basic_block(self.llfn));
diff --git a/src/librustc/middle/trans/foreign.rs b/src/librustc/middle/trans/foreign.rs
index 1ad5a543e66..edf003e3e52 100644
--- a/src/librustc/middle/trans/foreign.rs
+++ b/src/librustc/middle/trans/foreign.rs
@@ -197,7 +197,7 @@ fn build_wrap_fn_(ccx: @mut CrateContext,
// the C ABI.
if needs_c_return && !ty::type_is_immediate(ccx.tcx, tys.fn_sig.output) {
let lloutputtype = type_of::type_of(fcx.ccx, tys.fn_sig.output);
- fcx.llretptr = Some(alloca(raw_block(fcx, false, fcx.llstaticallocas),
+ fcx.llretptr = Some(alloca(raw_block(fcx, false, fcx.get_llstaticallocas()),
lloutputtype,
""));
}