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Auto merge of #122053 - erikdesjardins:alloca, r=nikic

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Stop using LLVM struct types for alloca

The alloca type has no semantic meaning, only the size (and alignment, but we specify it explicitly) matter. Using `[N x i8]` is a more direct way to specify that we want `N` bytes, and avoids relying on LLVM's struct layout. It is likely that a future LLVM version will change to an untyped alloca representation.

Split out from #121577.

r? `@ghost`
This commit is contained in:
bors 2024-04-24 03:00:44 +00:00
commit 752af44fc4
3 changed files with 7 additions and 13 deletions
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14
src/builder.rs
View File

@ -898,26 +898,20 @@ fn checked_binop(
self.gcc_checked_binop(oop, typ, lhs, rhs)
}
fn alloca(&mut self, ty: Type<'gcc>, align: Align) -> RValue<'gcc> {
// FIXME(antoyo): this check that we don't call get_aligned() a second time on a type.
// Ideally, we shouldn't need to do this check.
let aligned_type = if ty == self.cx.u128_type || ty == self.cx.i128_type {
ty
} else {
ty.get_aligned(align.bytes())
};
fn alloca(&mut self, size: Size, align: Align) -> RValue<'gcc> {
let ty = self.cx.type_array(self.cx.type_i8(), size.bytes()).get_aligned(align.bytes());
// TODO(antoyo): It might be better to return a LValue, but fixing the rustc API is non-trivial.
self.stack_var_count.set(self.stack_var_count.get() + 1);
self.current_func()
.new_local(
self.location,
aligned_type,
ty,
&format!("stack_var_{}", self.stack_var_count.get()),
)
.get_address(self.location)
}
fn byte_array_alloca(&mut self, _len: RValue<'gcc>, _align: Align) -> RValue<'gcc> {
fn dynamic_alloca(&mut self, _len: RValue<'gcc>, _align: Align) -> RValue<'gcc> {
unimplemented!();
}

2
src/intrinsic/mod.rs
View File

@ -531,7 +531,7 @@ fn store(
// We instead thus allocate some scratch space...
let scratch_size = cast.size(bx);
let scratch_align = cast.align(bx);
let llscratch = bx.alloca(cast.gcc_type(bx), scratch_align);
let llscratch = bx.alloca(scratch_size, scratch_align);
bx.lifetime_start(llscratch, scratch_size);
// ... where we first store the value...

4
src/intrinsic/simd.rs
View File

@ -18,7 +18,7 @@
use rustc_middle::ty::layout::HasTyCtxt;
use rustc_middle::ty::{self, Ty};
use rustc_span::{sym, Span, Symbol};
use rustc_target::abi::Align;
use rustc_target::abi::{Align, Size};
use crate::builder::Builder;
#[cfg(not(feature = "master"))]
@ -558,7 +558,7 @@ macro_rules! arith_binary {
let ze = bx.zext(result, bx.type_ix(expected_bytes * 8));
// Convert the integer to a byte array
let ptr = bx.alloca(bx.type_ix(expected_bytes * 8), Align::ONE);
let ptr = bx.alloca(Size::from_bytes(expected_bytes), Align::ONE);
bx.store(ze, ptr, Align::ONE);
let array_ty = bx.type_array(bx.type_i8(), expected_bytes);
let ptr = bx.pointercast(ptr, bx.cx.type_ptr_to(array_ty));