[SROA] Really remove associated dbg.declare when removing dead alloca

Summary:
There already was code that tried to remove the dbg.declare, but that code
was placed after we had called
 I->replaceAllUsesWith(UndefValue::get(I->getType()));
on the alloca, so when we searched for the relevant dbg.declare, we
couldn't find it.

Now we do the search before we call RAUW so there is a chance to find it.

An existing testcase needed update due to this. Two dbg.declare with undef
were removed and then suddenly one of the two CHECKS failed.

Before this patch we got

  call void @llvm.dbg.declare(metadata i24* undef, metadata !14, metadata !DIExpression(DW_OP_LLVM_fragment, 32, 24)), !dbg !15
  call void @llvm.dbg.declare(metadata %struct.prog_src_register* undef, metadata !14, metadata !DIExpression()), !dbg !15
  call void @llvm.dbg.value(metadata i32 0, metadata !14, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)), !dbg !15
  call void @llvm.dbg.value(metadata i32 0, metadata !14, metadata !DIExpression(DW_OP_LLVM_fragment, 32, 24)), !dbg !15

and with it we get

  call void @llvm.dbg.value(metadata i32 0, metadata !14, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)), !dbg !15
  call void @llvm.dbg.value(metadata i32 0, metadata !14, metadata !DIExpression(DW_OP_LLVM_fragment, 32, 24)), !dbg !15

However, the CHECKs in the testcase checked things in a silly order, so
they only passed since they found things in the first dbg.declare. Now
we changed the order of the checks and the test passes.

Reviewers: rnk

Reviewed By: rnk

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D37900

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313875 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index d5986a53aa9ba8a32a90dbcb7d2d4c6e52c74b2d..b968cb8c892b05c94cb571db9c64eab1fe1afb71 100644 (file)
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/lib/Transforms/Scalar/SROA.cpp
@@ -4247,6 +4247,15 @@ void SROA::deleteDeadInstructions(
     Instruction *I = DeadInsts.pop_back_val();
     DEBUG(dbgs() << "Deleting dead instruction: " << *I << "\n");
 
+    // If the instruction is an alloca, find the possible dbg.declare connected
+    // to it, and remove it too. We must do this before calling RAUW or we will
+    // not be able to find it.
+    if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
+      DeletedAllocas.insert(AI);
+      for (DbgInfoIntrinsic *OldDII : FindDbgAddrUses(AI))
+        OldDII->eraseFromParent();
+    }
+
     I->replaceAllUsesWith(UndefValue::get(I->getType()));
 
     for (Use &Operand : I->operands())
@@ -4257,12 +4266,6 @@ void SROA::deleteDeadInstructions(
           DeadInsts.insert(U);
       }
 
-    if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
-      DeletedAllocas.insert(AI);
-      for (DbgInfoIntrinsic *OldDII : FindDbgAddrUses(AI))
-        OldDII->eraseFromParent();
-    }
-
     ++NumDeleted;
     I->eraseFromParent();
   }

diff --git a/test/DebugInfo/X86/sroasplit-5.ll b/test/DebugInfo/X86/sroasplit-5.ll
index dbd3b49a6cbd38d232ab658b0cf2d2f584a0cf9a..78f5ca9a979b4fb3dbe7b11066f051a99667acea 100644 (file)
--- a/test/DebugInfo/X86/sroasplit-5.ll
+++ b/test/DebugInfo/X86/sroasplit-5.ll
@@ -20,10 +20,10 @@ target triple = "x86_64-unknown-linux-gnu"
 ;
 ; There should be no debug info for the padding.
 ; CHECK-NOT: DW_OP_LLVM_fragment, 56
-; CHECK: DIExpression(DW_OP_LLVM_fragment, 32, 24)
-; CHECK-NOT: DW_OP_LLVM_fragment, 56
 ; CHECK: DIExpression(DW_OP_LLVM_fragment, 0, 32)
 ; CHECK-NOT: DW_OP_LLVM_fragment, 56
+; CHECK: DIExpression(DW_OP_LLVM_fragment, 32, 24)
+; CHECK-NOT: DW_OP_LLVM_fragment, 56
 %struct.prog_src_register = type { i32, i24 }
 
 ; Function Attrs: nounwind

diff --git a/test/DebugInfo/X86/sroasplit-dbg-declare.ll b/test/DebugInfo/X86/sroasplit-dbg-declare.ll
new file mode 100644 (file)
index 0000000..0a1a41b
--- /dev/null
+++ b/test/DebugInfo/X86/sroasplit-dbg-declare.ll
@@ -0,0 +1,59 @@
+; RUN: opt -S -sroa -o - %s | FileCheck %s
+
+; SROA should split the alloca in two new ones, each with its own dbg.declare.
+; The original alloca and dbg.declare should be removed.
+
+define void @f1() {
+entry:
+  %0 = alloca [9 x i32]
+  call void @llvm.dbg.declare(metadata [9 x i32]* %0, metadata !11, metadata !DIExpression()), !dbg !17
+  %1 = bitcast [9 x i32]* %0 to i8*
+  call void @llvm.memset.p0i8.i64(i8* %1, i8 0, i64 36, i32 16, i1 true)
+  %2 = getelementptr [9 x i32], [9 x i32]* %0, i32 0, i32 0
+  store volatile i32 1, i32* %2
+  ret void
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i32, i1) #0
+
+attributes #0 = { argmemonly nounwind }
+attributes #1 = { nounwind readnone speculatable }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "foo.c", directory: "/bar")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 6.0.0"}
+!7 = distinct !DISubprogram(name: "f1", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !10)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null}
+!10 = !{!11}
+!11 = !DILocalVariable(name: "b", scope: !7, file: !1, line: 3, type: !12)
+!12 = !DICompositeType(tag: DW_TAG_array_type, baseType: !13, size: 288, elements: !15)
+!13 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !14)
+!14 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!15 = !{!16}
+!16 = !DISubrange(count: 9)
+!17 = !DILocation(line: 3, column: 18, scope: !7)
+
+; CHECK-NOT:  = alloca [9 x i32]
+; CHECK-NOT:  call void @llvm.dbg.declare(metadata [9 x i32]*
+
+; CHECK:      %[[VAR1:.*]] = alloca i32
+; CHECK-NEXT: %[[VAR2:.*]] = alloca [8 x i32]
+; CHECK-NEXT: call void @llvm.dbg.declare(metadata i32* %[[VAR1]]
+; CHECK-NEXT: call void @llvm.dbg.declare(metadata [8 x i32]* %[[VAR2]]
+
+; CHECK-NOT:  = alloca [9 x i32]
+; CHECK-NOT:  call void @llvm.dbg.declare(metadata [9 x i32]*
+