bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

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

Browse source 
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 29a56a3b1c
36 changed files with 234 additions and 226 deletions
Download patch file Download diff file Expand all files Collapse all files

2
compiler/rustc_codegen_llvm/src/abi.rs
View file

@ -227,7 +227,7 @@ impl<'ll, 'tcx> ArgAbiExt<'ll, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
// when passed by value, making it larger.
let copy_bytes = cmp::min(scratch_size.bytes(), self.layout.size.bytes());
// Allocate some scratch space...
let llscratch = bx.alloca(cast.llvm_type(bx), scratch_align);
let llscratch = bx.alloca(scratch_size, scratch_align);
bx.lifetime_start(llscratch, scratch_size);
// ...store the value...
bx.store(val, llscratch, scratch_align);

7
compiler/rustc_codegen_llvm/src/builder.rs
View file

@ -468,9 +468,10 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
val
}
fn alloca(&mut self, ty: &'ll Type, align: Align) -> &'ll Value {
fn alloca(&mut self, size: Size, align: Align) -> &'ll Value {
let mut bx = Builder::with_cx(self.cx);
bx.position_at_start(unsafe { llvm::LLVMGetFirstBasicBlock(self.llfn()) });
let ty = self.cx().type_array(self.cx().type_i8(), size.bytes());
unsafe {
let alloca = llvm::LLVMBuildAlloca(bx.llbuilder, ty, UNNAMED);
llvm::LLVMSetAlignment(alloca, align.bytes() as c_uint);
@ -478,10 +479,10 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
}
}
fn byte_array_alloca(&mut self, len: &'ll Value, align: Align) -> &'ll Value {
fn dynamic_alloca(&mut self, size: &'ll Value, align: Align) -> &'ll Value {
unsafe {
let alloca =
llvm::LLVMBuildArrayAlloca(self.llbuilder, self.cx().type_i8(), len, UNNAMED);
llvm::LLVMBuildArrayAlloca(self.llbuilder, self.cx().type_i8(), size, UNNAMED);
llvm::LLVMSetAlignment(alloca, align.bytes() as c_uint);
alloca
}

20
compiler/rustc_codegen_llvm/src/intrinsic.rs
View file

@ -18,7 +18,7 @@ use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf};
use rustc_middle::ty::{self, GenericArgsRef, Ty};
use rustc_middle::{bug, span_bug};
use rustc_span::{sym, Span, Symbol};
use rustc_target::abi::{self, Align, HasDataLayout, Primitive};
use rustc_target::abi::{self, Align, HasDataLayout, Primitive, Size};
use rustc_target::spec::{HasTargetSpec, PanicStrategy};
use std::cmp::Ordering;
@ -649,8 +649,9 @@ fn codegen_msvc_try<'ll>(
// }
//
// More information can be found in libstd's seh.rs implementation.
let ptr_size = bx.tcx().data_layout.pointer_size;
let ptr_align = bx.tcx().data_layout.pointer_align.abi;
let slot = bx.alloca(bx.type_ptr(), ptr_align);
let slot = bx.alloca(ptr_size, ptr_align);
let try_func_ty = bx.type_func(&[bx.type_ptr()], bx.type_void());
bx.invoke(try_func_ty, None, None, try_func, &[data], normal, catchswitch, None, None);
@ -920,15 +921,14 @@ fn codegen_emcc_try<'ll>(
// We need to pass two values to catch_func (ptr and is_rust_panic), so
// create an alloca and pass a pointer to that.
let ptr_size = bx.tcx().data_layout.pointer_size;
let ptr_align = bx.tcx().data_layout.pointer_align.abi;
let i8_align = bx.tcx().data_layout.i8_align.abi;
let catch_data_type = bx.type_struct(&[bx.type_ptr(), bx.type_bool()], false);
let catch_data = bx.alloca(catch_data_type, ptr_align);
let catch_data_0 =
bx.inbounds_gep(catch_data_type, catch_data, &[bx.const_usize(0), bx.const_usize(0)]);
bx.store(ptr, catch_data_0, ptr_align);
let catch_data_1 =
bx.inbounds_gep(catch_data_type, catch_data, &[bx.const_usize(0), bx.const_usize(1)]);
// Required in order for there to be no padding between the fields.
assert!(i8_align <= ptr_align);
let catch_data = bx.alloca(2 * ptr_size, ptr_align);
bx.store(ptr, catch_data, ptr_align);
let catch_data_1 = bx.inbounds_ptradd(catch_data, bx.const_usize(ptr_size.bytes()));
bx.store(is_rust_panic, catch_data_1, i8_align);
let catch_ty = bx.type_func(&[bx.type_ptr(), bx.type_ptr()], bx.type_void());
@ -1374,7 +1374,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
let ze = bx.zext(i_, 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);
return Ok(bx.load(array_ty, ptr, Align::ONE));