zig

commit e3e4af727103d90cb191f130159928d237263e1f (tree)
parent 1eb2e4801448aca29471bf6f7582135ddafb15fe
Author: Koakuma <koachan@protonmail.com>
Date:   Thu,  4 Feb 2021 20:51:53 +0700

stage1:	set gen_frame_size alignment to work around requirement mismatch

Explicitly set the alignment requirements to 1 (i.e, mark the load as unaligned)
since there are some architectures (e.g SPARCv9) which has different alignment
requirements between a function pointer and usize pointer. On those
architectures, not explicitly setting it will lead into @frameSize generating
usize-aligned load instruction that could crash if the function pointer happens
to be not usize-aligned.

Diffstat:
M
src/stage1/codegen.cpp
 | 
4
+++-

1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/stage1/codegen.cpp b/src/stage1/codegen.cpp
@@ -4160,7 +4160,9 @@ static LLVMValueRef gen_frame_size(CodeGen *g, LLVMValueRef fn_val) {
     LLVMValueRef casted_fn_val = LLVMBuildBitCast(g->builder, fn_val, ptr_usize_llvm_type, "");
     LLVMValueRef negative_one = LLVMConstInt(LLVMInt32Type(), -1, true);
     LLVMValueRef prefix_ptr = LLVMBuildInBoundsGEP(g->builder, casted_fn_val, &negative_one, 1, "");
-    return LLVMBuildLoad(g->builder, prefix_ptr, "");
+    LLVMValueRef load_inst = LLVMBuildLoad(g->builder, prefix_ptr, "");
+    LLVMSetAlignment(load_inst, 1);
+    return load_inst;
 }
 
 static void gen_init_stack_trace(CodeGen *g, LLVMValueRef trace_field_ptr, LLVMValueRef addrs_field_ptr) {