[llvm] r301210 - Use DW_OP_stack_value when reconstructing variable values with arithmetic.
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Mon Apr 24 11:11:42 PDT 2017
Author: adrian
Date: Mon Apr 24 13:11:42 2017
New Revision: 301210
URL: http://llvm.org/viewvc/llvm-project?rev=301210&view=rev
Log:
Use DW_OP_stack_value when reconstructing variable values with arithmetic.
When the location description of a source variable involves arithmetic
on the value itself, it needs to be marked with DW_OP_stack_value since it
is not describing the variable's location, but rather its value.
This is a follow-up to r297971 and fixes the source testcase quoted in
the comment in debuginfo-dce.ll.
rdar://problem/30725338
This reapplies r301093 without modifications.
Modified:
llvm/trunk/lib/Transforms/Utils/Local.cpp
llvm/trunk/test/Transforms/InstCombine/debuginfo-dce.ll
Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=301210&r1=301209&r2=301210&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/Local.cpp Mon Apr 24 13:11:42 2017
@@ -1268,21 +1268,37 @@ static void appendOffset(SmallVectorImpl
}
}
-/// Prepend \p DIExpr with a deref and offset operation.
+enum { WithStackValue = true };
+
+/// Prepend \p DIExpr with a deref and offset operation and optionally turn it
+/// into a stack value.
static DIExpression *prependDIExpr(DIBuilder &Builder, DIExpression *DIExpr,
- bool Deref, int64_t Offset) {
- if (!Deref && !Offset)
+ bool Deref, int64_t Offset = 0,
+ bool StackValue = false) {
+ if (!Deref && !Offset && !StackValue)
return DIExpr;
- // Create a copy of the original DIDescriptor for user variable, prepending
- // "deref" operation to a list of address elements, as new llvm.dbg.declare
- // will take a value storing address of the memory for variable, not
- // alloca itself.
- SmallVector<uint64_t, 4> Ops;
+
+ SmallVector<uint64_t, 8> Ops;
+ appendOffset(Ops, Offset);
if (Deref)
Ops.push_back(dwarf::DW_OP_deref);
- appendOffset(Ops, Offset);
if (DIExpr)
- Ops.append(DIExpr->elements_begin(), DIExpr->elements_end());
+ for (auto Op : DIExpr->expr_ops()) {
+ // A DW_OP_stack_value comes at the end, but before a DW_OP_LLVM_fragment.
+ if (StackValue) {
+ if (Op.getOp() == dwarf::DW_OP_stack_value)
+ StackValue = false;
+ else if (Op.getOp() == dwarf::DW_OP_LLVM_fragment) {
+ Ops.push_back(dwarf::DW_OP_stack_value);
+ StackValue = false;
+ }
+ }
+ Ops.push_back(Op.getOp());
+ for (unsigned I = 0; I < Op.getNumArgs(); ++I)
+ Ops.push_back(Op.getArg(I));
+ }
+ if (StackValue)
+ Ops.push_back(dwarf::DW_OP_stack_value);
return Builder.createExpression(Ops);
}
@@ -1374,12 +1390,15 @@ void llvm::salvageDebugInfo(Instruction
unsigned BitWidth =
M.getDataLayout().getPointerSizeInBits(GEP->getPointerAddressSpace());
APInt Offset(BitWidth, 0);
- // Rewrite a constant GEP into a DIExpression.
+ // Rewrite a constant GEP into a DIExpression. Since we are performing
+ // arithmetic to compute the variable's *value* in the DIExpression, we
+ // need to mark the expression with a DW_OP_stack_value.
if (GEP->accumulateConstantOffset(M.getDataLayout(), Offset)) {
auto *DIExpr = DVI->getExpression();
DIBuilder DIB(M, /*AllowUnresolved*/ false);
// GEP offsets are i32 and thus always fit into an int64_t.
- DIExpr = prependDIExpr(DIB, DIExpr, NoDeref, Offset.getSExtValue());
+ DIExpr = prependDIExpr(DIB, DIExpr, NoDeref, Offset.getSExtValue(),
+ WithStackValue);
DVI->setOperand(0, MDWrap(I.getOperand(0)));
DVI->setOperand(3, MetadataAsValue::get(I.getContext(), DIExpr));
DEBUG(dbgs() << "SALVAGE: " << *DVI << '\n');
@@ -1391,7 +1410,7 @@ void llvm::salvageDebugInfo(Instruction
// Rewrite the load into DW_OP_deref.
auto *DIExpr = DVI->getExpression();
DIBuilder DIB(M, /*AllowUnresolved*/ false);
- DIExpr = prependDIExpr(DIB, DIExpr, WithDeref, 0);
+ DIExpr = prependDIExpr(DIB, DIExpr, WithDeref);
DVI->setOperand(0, MDWrap(I.getOperand(0)));
DVI->setOperand(3, MetadataAsValue::get(I.getContext(), DIExpr));
DEBUG(dbgs() << "SALVAGE: " << *DVI << '\n');
Modified: llvm/trunk/test/Transforms/InstCombine/debuginfo-dce.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/debuginfo-dce.ll?rev=301210&r1=301209&r2=301210&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/debuginfo-dce.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/debuginfo-dce.ll Mon Apr 24 13:11:42 2017
@@ -23,7 +23,6 @@ target triple = "x86_64-apple-macosx10.1
%struct.entry = type { %struct.entry* }
-; Function Attrs: nounwind ssp uwtable
define void @salvage_load(%struct.entry** %queue) local_unnamed_addr #0 !dbg !14 {
entry:
%im_not_dead = alloca %struct.entry*
@@ -38,7 +37,6 @@ entry:
ret void, !dbg !21
}
-; Function Attrs: nounwind ssp uwtable
define void @salvage_bitcast(%struct.entry* %queue) local_unnamed_addr #0 !dbg !14 {
entry:
%im_not_dead = alloca i8*
@@ -53,24 +51,54 @@ entry:
ret void, !dbg !21
}
-; Function Attrs: nounwind ssp uwtable
-define void @salvage_gep(%struct.entry* %queue, %struct.entry* %end) local_unnamed_addr #0 !dbg !14 {
+define void @salvage_gep0(%struct.entry* %queue, %struct.entry* %end) local_unnamed_addr #0 !dbg !14 {
entry:
%im_not_dead = alloca %struct.entry**
%0 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19
%1 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19
call void @llvm.dbg.value(metadata %struct.entry** %1, i64 0, metadata !18, metadata !20), !dbg !19
-; CHECK: define void @salvage_gep
+; CHECK: define void @salvage_gep0
; CHECK-NEXT: entry:
; CHECK-NEXT: call void @llvm.dbg.value(metadata %struct.entry* %queue, i64 0,
-; CHECK-SAME: metadata ![[GEP_EXPR:[0-9]+]])
+; CHECK-SAME: metadata ![[GEP0_EXPR:[0-9]+]])
+ store %struct.entry** %1, %struct.entry*** %im_not_dead, align 8
+ ret void, !dbg !21
+}
+
+define void @salvage_gep1(%struct.entry* %queue, %struct.entry* %end) local_unnamed_addr #0 !dbg !14 {
+entry:
+ %im_not_dead = alloca %struct.entry**
+ %0 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19
+ %1 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19
+ call void @llvm.dbg.value(metadata %struct.entry** %1, i64 0, metadata !18, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)), !dbg !19
+; CHECK: define void @salvage_gep1
+; CHECK-NEXT: entry:
+; CHECK-NEXT: call void @llvm.dbg.value(metadata %struct.entry* %queue, i64 0,
+; CHECK-SAME: metadata ![[GEP1_EXPR:[0-9]+]])
+ store %struct.entry** %1, %struct.entry*** %im_not_dead, align 8
+ ret void, !dbg !21
+}
+
+define void @salvage_gep2(%struct.entry* %queue, %struct.entry* %end) local_unnamed_addr #0 !dbg !14 {
+entry:
+ %im_not_dead = alloca %struct.entry**
+ %0 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19
+ %1 = getelementptr inbounds %struct.entry, %struct.entry* %queue, i32 -1, i32 0, !dbg !19
+ call void @llvm.dbg.value(metadata %struct.entry** %1, i64 0, metadata !18, metadata !DIExpression(DW_OP_stack_value)), !dbg !19
+; CHECK: define void @salvage_gep2
+; CHECK-NEXT: entry:
+; CHECK-NEXT: call void @llvm.dbg.value(metadata %struct.entry* %queue, i64 0,
+; CHECK-SAME: metadata ![[GEP2_EXPR:[0-9]+]])
store %struct.entry** %1, %struct.entry*** %im_not_dead, align 8
ret void, !dbg !21
}
; CHECK: ![[LOAD_EXPR]] = !DIExpression(DW_OP_deref, DW_OP_plus, 0)
; CHECK: ![[BITCAST_EXPR]] = !DIExpression(DW_OP_plus, 0)
-; CHECK: ![[GEP_EXPR]] = !DIExpression(DW_OP_minus, 8, DW_OP_plus, 0)
+; CHECK: ![[GEP0_EXPR]] = !DIExpression(DW_OP_minus, 8, DW_OP_plus, 0, DW_OP_stack_value)
+; CHECK: ![[GEP1_EXPR]] = !DIExpression(DW_OP_minus, 8, DW_OP_stack_value,
+; CHECK-SAME: DW_OP_LLVM_fragment, 0, 32)
+; CHECK: ![[GEP2_EXPR]] = !DIExpression(DW_OP_minus, 8, DW_OP_stack_value)
; Function Attrs: nounwind readnone
declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
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