[SafeStack] Insert the deref before remaining elements

This is a follow up to D64971. While we need to insert the deref after
the offset, it needs to come before the remaining elements in the
original expression since the deref needs to happen before the LLVM
fragment if present.

Differential Revision: https://reviews.llvm.org/D65172

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366865 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index b6d555cd13e7a946838e3b8a7f72ccafb458ed2c..8e501728599b36266add21fcf4c447e542da2d21 100644 (file)
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -1599,13 +1599,8 @@ static void replaceOneDbgValueForAlloca(DbgValueInst *DVI, Value *NewAddress,
 
   // Insert the offset before the first deref.
   // We could just change the offset argument of dbg.value, but it's unsigned...
-  if (Offset) {
-    SmallVector<uint64_t, 4> Ops;
-    DIExpression::appendOffset(Ops, Offset);
-    Ops.append(DIExpr->elements_begin() + 1, DIExpr->elements_end());
-    Ops.push_back(dwarf::DW_OP_deref);
-    DIExpr = Builder.createExpression(Ops);
-  }
+  if (Offset)
+    DIExpr = DIExpression::prepend(DIExpr, 0, Offset);
 
   Builder.insertDbgValueIntrinsic(NewAddress, DIVar, DIExpr, Loc, DVI);
   DVI->eraseFromParent();

diff --git a/test/Transforms/SafeStack/X86/debug-loc2.ll b/test/Transforms/SafeStack/X86/debug-loc2.ll
index 30623962691f9200ef4dea0d7f191e0a903da934..79b6c10ed7d9a7866286deb5e7993365c53eab4c 100644 (file)
--- a/test/Transforms/SafeStack/X86/debug-loc2.ll
+++ b/test/Transforms/SafeStack/X86/debug-loc2.ll
@@ -24,6 +24,10 @@ entry:
 ; CHECK: call void @llvm.dbg.value(metadata ![[EMPTY]], metadata !{{.*}}, metadata !{{.*}})
   tail call void @llvm.dbg.value(metadata i32* %x1, metadata !10, metadata !24), !dbg !16
 
+; Supported dbg.value: rewritted based on the [[USP]] value.
+; CHECK: call void @llvm.dbg.value(metadata i8* %[[USP]], metadata ![[X1:.*]], metadata !DIExpression(DW_OP_constu, 4, DW_OP_minus, DW_OP_deref, DW_OP_LLVM_fragment, 0, 4))
+  tail call void @llvm.dbg.value(metadata i32* %x1, metadata !10, metadata !25), !dbg !16
+
 ; Supported dbg.value: rewritted based on the [[USP]] value.
 ; CHECK: call void @llvm.dbg.value(metadata i8* %[[USP]], metadata ![[X1:.*]], metadata !DIExpression(DW_OP_constu, 4, DW_OP_minus, DW_OP_deref))
   tail call void @llvm.dbg.value(metadata i32* %x1, metadata !10, metadata !15), !dbg !16
@@ -94,3 +98,4 @@ attributes #4 = { nounwind }
 !22 = !DILexicalBlockFile(scope: !6, file: !1, discriminator: 1)
 !23 = !DIExpression()
 !24 = !DIExpression(DW_OP_constu, 42, DW_OP_minus)
+!25 = !DIExpression(DW_OP_deref, DW_OP_LLVM_fragment, 0, 4)