[Utils] Salvage the debug info of DCE'ed 'sub' instructions

This salvages 14 debug values in a stage2 build of clang.

llvm-svn: 324974

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 13668e7..379b6bf 100644 (file)
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1546,6 +1546,9 @@ void llvm::salvageDebugInfo(Instruction &I) {
       case Instruction::Add:
         applyOffset(DII, Val);
         break;
+      case Instruction::Sub:
+        applyOffset(DII, -int64_t(Val));
+        break;
       case Instruction::Or:
         applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_or});
         break;

diff --git a/llvm/test/Transforms/InstCombine/debuginfo-variables.ll b/llvm/test/Transforms/InstCombine/debuginfo-variables.ll
index d2cd7ea..fec0de7 100644 (file)
--- a/llvm/test/Transforms/InstCombine/debuginfo-variables.ll
+++ b/llvm/test/Transforms/InstCombine/debuginfo-variables.ll
@@ -24,6 +24,20 @@ define void @test_xor(i32 %A) {
   ret void
 }
 
+define void @test_sub_neg(i64 %A) {
+; CHECK-LABEL: @test_sub_neg(
+; CHECK-NEXT:  call void @llvm.dbg.value(metadata i64 %A, metadata !27, metadata !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value)), !dbg !28
+  %1 = sub i64 %A, -1
+  ret void
+}
+
+define void @test_sub_pos(i64 %A) {
+; CHECK-LABEL: @test_sub_pos(
+; CHECK-NEXT:  call void @llvm.dbg.value(metadata i64 %A, metadata !32, metadata !DIExpression(DW_OP_constu, 1, DW_OP_minus, DW_OP_stack_value)), !dbg !33
+  %1 = sub i64 %A, 1
+  ret void
+}
+
 ; CHECK: !8 = !DILocalVariable(name: "1", scope: !5, file: !1, line: 1, type: !9)
 ; CHECK: !10 = !DILocalVariable(name: "2", scope: !5, file: !1, line: 2, type: !11)
 ; CHECK: !12 = !DILocation(line: 2, column: 1, scope: !5)
@@ -34,3 +48,9 @@ define void @test_xor(i32 %A) {
 
 ; CHECK: !22 = !DILocalVariable(name: "4", scope: !20, file: !1, line: 6, type: !9)
 ; CHECK: !23 = !DILocation(line: 6, column: 1, scope: !20)
+
+; CHECK: !27 = !DILocalVariable(name: "5", scope: !25, file: !1, line: 8, type: !11)
+; CHECK: !28 = !DILocation(line: 8, column: 1, scope: !25)
+
+; CHECK: !32 = !DILocalVariable(name: "6", scope: !30, file: !1, line: 10, type: !11)
+; CHECK: !33 = !DILocation(line: 10, column: 1, scope: !30)