GlobalDCE: Teach isEmptyFunction() to ignore debug intrinsics.
This fixes PR39669.
https://bugs.llvm.org/show_bug.cgi?id=39669
llvm-svn: 347065
diff --git a/llvm/lib/Transforms/IPO/GlobalDCE.cpp b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
index c77ea04..34de874 100644
--- a/llvm/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
@@ -19,6 +19,7 @@
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/IPO.h"
@@ -75,13 +76,17 @@
return new GlobalDCELegacyPass();
}
-/// Returns true if F contains only a single "ret" instruction.
+/// Returns true if F is effectively empty.
static bool isEmptyFunction(Function *F) {
BasicBlock &Entry = F->getEntryBlock();
- if (Entry.size() != 1 || !isa<ReturnInst>(Entry.front()))
- return false;
- ReturnInst &RI = cast<ReturnInst>(Entry.front());
- return RI.getReturnValue() == nullptr;
+ for (auto &I : Entry) {
+ if (isa<DbgInfoIntrinsic>(I))
+ continue;
+ if (auto *RI = dyn_cast<ReturnInst>(&I))
+ return !RI->getReturnValue();
+ break;
+ }
+ return false;
}
/// Compute the set of GlobalValue that depends from V.
diff --git a/llvm/test/Transforms/GlobalDCE/global_ctors.ll b/llvm/test/Transforms/GlobalDCE/global_ctors.ll
index 91bb9ab..bd1a97e 100644
--- a/llvm/test/Transforms/GlobalDCE/global_ctors.ll
+++ b/llvm/test/Transforms/GlobalDCE/global_ctors.ll
@@ -1,14 +1,37 @@
; RUN: opt -S -globaldce < %s | FileCheck %s
+; Test that the presence of debug intrinsics isn't affecting GlobalDCE.
; CHECK: @llvm.global_ctors = appending global [1 x { i32, void ()* }] [{ i32, void ()* } { i32 65535, void ()* @_notremovable }]
; CHECK-NOT: @_GLOBAL__I_a
declare void @_notremovable()
-@llvm.global_ctors = appending global [2 x { i32, void ()* }] [{ i32, void ()* } { i32 65535, void ()* @_GLOBAL__I_a }, { i32, void ()* } { i32 65535, void ()* @_notremovable }]
+@llvm.global_ctors = appending global [3 x { i32, void ()* }] [{ i32, void ()* } { i32 65535, void ()* @_GLOBAL__I_a }, { i32, void ()* } { i32 65535, void ()* @_GLOBAL__I_b }, { i32, void ()* } { i32 65535, void ()* @_notremovable }]
+
+@x = internal unnamed_addr constant i8 undef, align 1
; Function Attrs: nounwind readnone
define internal void @_GLOBAL__I_a() #1 section "__TEXT,__StaticInit,regular,pure_instructions" {
entry:
ret void
}
+
+; Function Attrs: nounwind readnone
+define internal void @_GLOBAL__I_b() #1 section "__TEXT,__StaticInit,regular,pure_instructions" {
+entry:
+ tail call void @llvm.dbg.value(metadata i8* @x, metadata !4, metadata !DIExpression(DW_OP_deref, DW_OP_constu, 0, DW_OP_swap, DW_OP_xderef)), !dbg !5
+ ret void
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.module.flags = !{!0}
+!llvm.dbg.cu = !{!1}
+
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+!1 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !2, emissionKind: FullDebug)
+!2 = !DIFile(filename: "filename", directory: "directory")
+!3 = distinct !DISubprogram(name: "h1", unit: !1)
+!4 = !DILocalVariable(name: "b", arg: 1, scope: !3)
+!5 = !DILocation(scope: !3)