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Remove PrologEpilogInserter's usage of DBG_VALUE's offset field

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In the last half-dozen commits to LLVM I removed code that became dead
after removing the offset parameter from llvm.dbg.value gradually
proceeding from IR towards the backend. Before I can move on to
DwarfDebug and friends there is one last side-called offset I need to
remove:  This patch modifies PrologEpilogInserter's use of the
DBG_VALUE's offset argument to use a DIExpression instead. Because the
PrologEpilogInserter runs at the Machine level I had to play a little
trick with a named llvm.dbg.mir node to get the DIExpressions to print
in MIR dumps (which print the llvm::Module followed by the
MachineFunction dump).

I also had to add rudimentary DwarfExpression support to CodeView and
as a side-effect also fixed a bug (CodeViewDebug::collectVariableInfo
was supposed to give up on variables with complex DIExpressions, but
would fail to do so for fragments, which are also modeled as
DIExpressions).

With this last holdover removed we will have only one canonical way of
representing offsets to debug locations which will simplify the code
in DwarfDebug (and future versions of CodeViewDebug once it starts
handling more complex expressions) and make it easier to reason about.

This patch is NFC-ish: All test case changes are for assembler
comments and the binary output does not change.

rdar://problem/33580047
Differential Revision: https://reviews.llvm.org/D36125

llvm-svn: 309751
This commit is contained in:
Adrian Prantl 2017-08-01 21:45:24 +00:00
parent 1ba7c27bcc
commit 431b172354
12 changed files with 42 additions and 18 deletions
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5
include/llvm/CodeGen/MachineOperand.h
View File

@ -549,6 +549,11 @@ public:
Contents.OffsetedInfo.Val.Index = Idx;
}
void setMetadata(const MDNode *MD) {
assert(isMetadata() && "Wrong MachineOperand mutator");
Contents.MD = MD;
}
void setMBB(MachineBasicBlock *MBB) {
assert(isMBB() && "Wrong MachineOperand mutator");
Contents.MBB = MBB;

21
lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
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@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "CodeViewDebug.h"
#include "DwarfExpression.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
@ -983,17 +984,29 @@ void CodeViewDebug::collectVariableInfo(const DISubprogram *SP) {
const MachineInstr *DVInst = Range.first;
assert(DVInst->isDebugValue() && "Invalid History entry");
const DIExpression *DIExpr = DVInst->getDebugExpression();
bool InMemory = DVInst->getOperand(1).isImm();
bool IsSubfield = false;
unsigned StructOffset = 0;
// Recognize a +Offset expression.
int Offset = 0;
DIExpressionCursor Ops(DIExpr);
auto Op = Ops.peek();
if (Op && Op->getOp() == dwarf::DW_OP_plus_uconst) {
Offset = Op->getArg(0);
Ops.take();
}
// Handle fragments.
auto Fragment = DIExpr->getFragmentInfo();
auto Fragment = Ops.getFragmentInfo();
if (Fragment) {
IsSubfield = true;
StructOffset = Fragment->OffsetInBits / 8;
} else if (DIExpr->getNumElements() > 0) {
continue; // Ignore unrecognized exprs.
}
// Ignore unrecognized exprs.
if (Ops.peek() && Ops.peek()->getOp() != dwarf::DW_OP_LLVM_fragment)
continue;
if (!InMemory && Offset)
continue;
// Bail if operand 0 is not a valid register. This means the variable is a
// simple constant, or is described by a complex expression.
@ -1006,8 +1019,6 @@ void CodeViewDebug::collectVariableInfo(const DISubprogram *SP) {
// Handle the two cases we can handle: indirect in memory and in register.
unsigned CVReg = TRI->getCodeViewRegNum(Reg);
bool InMemory = DVInst->getOperand(1).isImm();
int Offset = InMemory ? DVInst->getOperand(1).getImm() : 0;
{
LocalVarDefRange DR;
DR.CVRegister = CVReg;

4
lib/CodeGen/MachineModuleInfo.cpp
View File

@ -16,6 +16,7 @@
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
@ -209,7 +210,8 @@ bool MachineModuleInfo::doInitialization(Module &M) {
DbgInfoAvailable = UsesVAFloatArgument = UsesMorestackAddr = false;
AddrLabelSymbols = nullptr;
TheModule = &M;
if (getDebugMetadataVersionFromModule(M))
M.getOrInsertNamedMetadata("llvm.dbg.mir");
return false;
}

13
lib/CodeGen/PrologEpilogInserter.cpp
View File

@ -31,6 +31,7 @@
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/CodeGen/StackProtector.h"
#include "llvm/CodeGen/WinEHFuncInfo.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/LLVMContext.h"
@ -1079,11 +1080,15 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn,
assert(i == 0 && "Frame indices can only appear as the first "
"operand of a DBG_VALUE machine instruction");
unsigned Reg;
MachineOperand &Offset = MI.getOperand(1);
Offset.setImm(
Offset.getImm() +
TFI->getFrameIndexReference(Fn, MI.getOperand(0).getIndex(), Reg));
int64_t Offset =
TFI->getFrameIndexReference(Fn, MI.getOperand(0).getIndex(), Reg);
MI.getOperand(0).ChangeToRegister(Reg, false /*isDef*/);
auto *DIExpr = DIExpression::prepend(MI.getDebugExpression(),
DIExpression::NoDeref, Offset);
MI.getOperand(3).setMetadata(DIExpr);
const Module *M = Fn.getMMI().getModule();
// Add the expression to the metadata graph so isn't lost in MIR dumps.
M->getNamedMetadata("llvm.dbg.mir")->addOperand(DIExpr);
continue;
}

2
lib/IR/Verifier.cpp
View File

@ -736,7 +736,7 @@ void Verifier::visitNamedMDNode(const NamedMDNode &NMD) {
// There used to be various other llvm.dbg.* nodes, but we don't support
// upgrading them and we want to reserve the namespace for future uses.
if (NMD.getName().startswith("llvm.dbg."))
AssertDI(NMD.getName() == "llvm.dbg.cu",
AssertDI(NMD.getName() == "llvm.dbg.cu" || NMD.getName() == "llvm.dbg.mir",
"unrecognized named metadata node in the llvm.dbg namespace",
&NMD);
for (const MDNode *MD : NMD.operands()) {

2
test/CodeGen/ARM/debug-info-arg.ll
View File

@ -11,7 +11,7 @@ define void @foo(%struct.tag_s* nocapture %this, %struct.tag_s* %c, i64 %x, i64
tail call void @llvm.dbg.value(metadata %struct.tag_s* %c, metadata !13, metadata !DIExpression()), !dbg !21
tail call void @llvm.dbg.value(metadata i64 %x, metadata !14, metadata !DIExpression()), !dbg !22
tail call void @llvm.dbg.value(metadata i64 %y, metadata !17, metadata !DIExpression()), !dbg !23
;CHECK: @DEBUG_VALUE: foo:y <- [%R7+8]
;CHECK: @DEBUG_VALUE: foo:y <- [DW_OP_plus_uconst 8] [%R7+0]
tail call void @llvm.dbg.value(metadata %struct.tag_s* %ptr1, metadata !18, metadata !DIExpression()), !dbg !24
tail call void @llvm.dbg.value(metadata %struct.tag_s* %ptr2, metadata !19, metadata !DIExpression()), !dbg !25
%1 = icmp eq %struct.tag_s* %c, null, !dbg !26

2
test/DebugInfo/ARM/PR16736.ll
View File

@ -2,7 +2,7 @@
; RUN: llc -filetype=obj < %s \
; RUN: | llvm-dwarfdump - | FileCheck %s --check-prefix=DWARF
;
; CHECK: @DEBUG_VALUE: h:x <- [%R{{.*}}+{{.*}}]
; CHECK: @DEBUG_VALUE: h:x <- [DW_OP_plus_uconst {{.*}}] [%R{{.*}}+0]
; DWARF: Location description: {{7[0-9] [0-9]+ $}}
; DW_OP_breg. +..
; generated from:

2
test/DebugInfo/COFF/pieces.ll
View File

@ -89,7 +89,7 @@
; ASM: callq g
; ASM: movl %eax, [[offset_o_x:[0-9]+]](%rsp) # 4-byte Spill
; ASM: [[spill_o_x_start:\.Ltmp[0-9]+]]:
; ASM: #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_LLVM_fragment 32 32] [%RSP+[[offset_o_x]]]
; ASM: #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_plus_uconst [[offset_o_x]], DW_OP_LLVM_fragment 32 32] [%RSP+0]
; ASM: #APP
; ASM: #NO_APP
; ASM: movl [[offset_o_x]](%rsp), %eax # 4-byte Reload

3
test/DebugInfo/X86/bbjoin.ll
View File

@ -9,10 +9,11 @@
; ++x;
; return x; // check that x is not a constant here.
; }
; CHECK: ![[EXPR:.*]] = !DIExpression(DW_OP_plus_uconst, 4, DW_OP_deref)
; CHECK: ![[X:.*]] = !DILocalVariable(name: "x",
; CHECK: bb.0.entry:
; CHECK: DBG_VALUE 23, 0, ![[X]],
; CHECK: DBG_VALUE %rsp, 4, ![[X]]
; CHECK: DBG_VALUE %rsp, 0, ![[X]], ![[EXPR]],
; CHECK: bb.1.if.then:
; CHECK: DBG_VALUE 43, 0, ![[X]],
; CHECK: bb.2.if.end:

2
test/DebugInfo/X86/dbg-value-frame-index.ll
View File

@ -20,7 +20,7 @@ while.end:
}
; CHECK-LABEL: test
; CHECK: #DEBUG_VALUE: test:w <- [%RSP+8]
; CHECK: #DEBUG_VALUE: test:w <- [DW_OP_plus_uconst 8] [%RSP+0]
; DWARF: Location description: 77 08
; DW_OP_breg7 +8

2
test/DebugInfo/X86/debug-loc-asan.ll
View File

@ -17,7 +17,7 @@
; CHECK: #DEBUG_VALUE: bar:y <- [DW_OP_deref] [%RDI+0]
; CHECK: movq %rdi, [[OFFSET:[0-9]+]](%rsp)
; CHECK-NEXT: [[START_LABEL:.Ltmp[0-9]+]]
; CHECK-NEXT: #DEBUG_VALUE: bar:y <- [DW_OP_deref, DW_OP_deref]
; CHECK-NEXT: #DEBUG_VALUE: bar:y <- [DW_OP_plus_uconst [[OFFSET]], DW_OP_deref, DW_OP_deref]
; This location should be valid until the end of the function.
; CHECK: movq %rbp, %rsp

2
test/DebugInfo/X86/pieces-4.ll
View File

@ -17,7 +17,7 @@
; CHECK: callq g
; CHECK: movl %eax, [[offs:[0-9]+]](%rsp) # 4-byte Spill
; CHECK: #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_LLVM_fragment 32 32] 0
; CHECK: #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_LLVM_fragment 0 32] [%RSP+[[offs]]]
; CHECK: #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_plus_uconst [[offs]], DW_OP_LLVM_fragment 0 32] [%RSP+0]
; CHECK: #APP
; CHECK: #NO_APP
; CHECK: movl [[offs]](%rsp), %eax # 4-byte Reload