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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
parent c1feb3ecee 6df27ef88f
commit 29a56a3b1c
36 changed files with 234 additions and 226 deletions
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7
compiler/rustc_codegen_llvm/src/builder.rs
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@@ -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
}