diff --git a/llvm/test/CodeGen/X86/bug46195.ll b/llvm/test/CodeGen/X86/bug46195.ll new file mode 100644 --- /dev/null +++ b/llvm/test/CodeGen/X86/bug46195.ll @@ -0,0 +1,59 @@ +; RUN: llc < %s -O1 -o /dev/null -debug-only=isel 2>&1 | FileCheck %s +; +; Verify that DAGCombiner preserves the correct dependency chain for +; promoted loads. +; +; Generated from the following example, compiled with -O1: +; +; struct S { +; int x; +; unsigned short y; +; }; +; +; extern void maybe_mutate(struct S *ptr); +; +; void translate(struct S *ptr) { +; unsigned short c = ptr->y; +; maybe_mutate(ptr); +; ptr->y = 2 | 0x200 | (c & (0x3f | 0x8000)); +; } + +source_filename = "repro.c" +target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +%struct.S = type { i32, i16 } + +define dso_local void @translate(%struct.S* %ptr) local_unnamed_addr #0 { +entry: + %y = getelementptr inbounds %struct.S, %struct.S* %ptr, i64 0, i32 1 + %0 = load i16, i16* %y, align 4, !tbaa !2 + call void @maybe_mutate(%struct.S* %ptr) #2 + %1 = and i16 %0, -32707 + %2 = or i16 %1, 514 + store i16 %2, i16* %y, align 4, !tbaa !2 + ret void +} + +declare dso_local void @maybe_mutate(%struct.S*) #2 + +!llvm.module.flags = !{!0} +!llvm.ident = !{!1} + +!0 = !{i32 1, !"wchar_size", i32 4} +!1 = !{!"clang version 11.0.0 (https://github.com/llvm/llvm-project b28167928d2722e8774da3fce8b3307a0fa27245)"} +!2 = !{!3, !7, i64 4} +!3 = !{!"S", !4, i64 0, !7, i64 4} +!4 = !{!"int", !5, i64 0} +!5 = !{!"omnipotent char", !6, i64 0} +!6 = !{!"Simple C/C++ TBAA"} +!7 = !{!"short", !5, i64 0} + +; Verify that the load of `y` is ordered before the call to +; `maybe_mutate()`. +; +; CHECK: Optimized legalized selection DAG: %bb.0 'translate:entry' +; CHECK: SelectionDAG has {{.*}} nodes: +; CHECK-DAG: {{.*}}callseq_start [[LOAD:t[0-9]+]]:1, +; CHECK-DAG: [[LOAD]]: i32,ch = load<(load 2 from %ir.y, +; CHECK: ===== Instruction selection begins: %bb.0 'entry'