[llvm] r369092 - [DebugInfo] Handle complex expressions with spills in LiveDebugValues
Jeremy Morse via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 16 03:04:17 PDT 2019
Author: jmorse
Date: Fri Aug 16 03:04:17 2019
New Revision: 369092
URL: http://llvm.org/viewvc/llvm-project?rev=369092&view=rev
Log:
[DebugInfo] Handle complex expressions with spills in LiveDebugValues
In r369026 we disabled spill-recognition in LiveDebugValues for anything
that has a complex expression. This is because it's hard to recover the
complex expression once the spill location is baked into it.
This patch re-enables spill-recognition and slightly adjusts the DBG_VALUE
insts that LiveDebugValues tracks: instead of tracking the last DBG_VALUE
for a variable, it tracks the last _unspilt_ DBG_VALUE. The spill-restore
code is then able to access and copy the original complex expression; but
the rest of LiveDebugValues has to be aware of the slight semantic shift,
and produce a new spilt location if a spilt location is propagated between
blocks.
The test added produces an incorrect variable location (see FIXME), which
will be the subject of future work.
Differential Revision: https://reviews.llvm.org/D65368
Modified:
llvm/trunk/lib/CodeGen/LiveDebugValues.cpp
llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir
Modified: llvm/trunk/lib/CodeGen/LiveDebugValues.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveDebugValues.cpp?rev=369092&r1=369091&r2=369092&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/LiveDebugValues.cpp (original)
+++ llvm/trunk/lib/CodeGen/LiveDebugValues.cpp Fri Aug 16 03:04:17 2019
@@ -227,8 +227,8 @@ private:
/// The constructor for spill locations.
VarLoc(const MachineInstr &MI, unsigned SpillBase, int SpillOffset,
- LexicalScopes &LS)
- : Var(MI), MI(MI), UVS(MI.getDebugLoc(), LS) {
+ LexicalScopes &LS, const MachineInstr &OrigMI)
+ : Var(MI), MI(OrigMI), UVS(MI.getDebugLoc(), LS) {
assert(MI.isDebugValue() && "not a DBG_VALUE");
assert(MI.getNumOperands() == 4 && "malformed DBG_VALUE");
Kind = SpillLocKind;
@@ -567,11 +567,7 @@ void LiveDebugValues::transferDebugValue
ID = VarLocIDs.insert(VL);
OpenRanges.insert(ID, VL.Var);
} else if (MI.hasOneMemOperand()) {
- // It's a stack spill -- fetch spill base and offset.
- VarLoc::SpillLoc SpillLocation = extractSpillBaseRegAndOffset(MI);
- VarLoc VL(MI, SpillLocation.SpillBase, SpillLocation.SpillOffset, LS);
- ID = VarLocIDs.insert(VL);
- OpenRanges.insert(ID, VL.Var);
+ llvm_unreachable("DBG_VALUE with mem operand encountered after regalloc?");
} else {
// This must be an undefined location. We should leave OpenRanges closed.
assert(MI.getOperand(0).isReg() && MI.getOperand(0).getReg() == 0 &&
@@ -678,7 +674,7 @@ void LiveDebugValues::insertTransferDebu
*MF, DebugInstr->getDebugLoc(), DebugInstr->getDesc(), true,
SpillLocation.SpillBase, DebugInstr->getDebugVariable(), SpillExpr);
VarLoc VL(*NewDebugInstr, SpillLocation.SpillBase,
- SpillLocation.SpillOffset, LS);
+ SpillLocation.SpillOffset, LS, *DebugInstr);
ProcessVarLoc(VL, NewDebugInstr);
LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for spill: ";
NewDebugInstr->print(dbgs(), /*IsStandalone*/false,
@@ -691,17 +687,11 @@ void LiveDebugValues::insertTransferDebu
"No register supplied when handling a restore of a debug value");
MachineFunction *MF = MI.getMF();
DIBuilder DIB(*const_cast<Function &>(MF->getFunction()).getParent());
-
- const DIExpression *NewExpr;
- if (auto Fragment = DebugInstr->getDebugExpression()->getFragmentInfo())
- NewExpr = *DIExpression::createFragmentExpression(DIB.createExpression(),
- Fragment->OffsetInBits, Fragment->SizeInBits);
- else
- NewExpr = DIB.createExpression();
-
- NewDebugInstr =
- BuildMI(*MF, DebugInstr->getDebugLoc(), DebugInstr->getDesc(), false,
- NewReg, DebugInstr->getDebugVariable(), NewExpr);
+ // DebugInstr refers to the pre-spill location, therefore we can reuse
+ // its expression.
+ NewDebugInstr = BuildMI(
+ *MF, DebugInstr->getDebugLoc(), DebugInstr->getDesc(), false, NewReg,
+ DebugInstr->getDebugVariable(), DebugInstr->getDebugExpression());
VarLoc VL(*NewDebugInstr, LS);
ProcessVarLoc(VL, NewDebugInstr);
LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for register restore: ";
@@ -856,14 +846,9 @@ void LiveDebugValues::transferSpillOrRes
<< "\n");
}
// Check if the register or spill location is the location of a debug value.
- // FIXME: Don't create a spill transfer if there is a complex expression,
- // because we currently cannot recover the original expression on restore.
for (unsigned ID : OpenRanges.getVarLocs()) {
- const MachineInstr *DebugInstr = &VarLocIDs[ID].MI;
-
if (TKind == TransferKind::TransferSpill &&
- VarLocIDs[ID].isDescribedByReg() == Reg &&
- !DebugInstr->getDebugExpression()->isComplex()) {
+ VarLocIDs[ID].isDescribedByReg() == Reg) {
LLVM_DEBUG(dbgs() << "Spilling Register " << printReg(Reg, TRI) << '('
<< VarLocIDs[ID].Var.getVar()->getName() << ")\n");
} else if (TKind == TransferKind::TransferRestore &&
@@ -1121,13 +1106,24 @@ bool LiveDebugValues::join(
DebugInstr->getDebugVariable(),
DebugInstr->getDebugExpression());
} else {
+ auto *DebugExpr = DebugInstr->getDebugExpression();
+ Register Reg = DebugInstr->getOperand(0).getReg();
+ bool IsIndirect = DebugInstr->isIndirectDebugValue();
+
+ if (DiffIt.Kind == VarLoc::SpillLocKind) {
+ // This is is a spilt location; DebugInstr refers to the unspilt
+ // location. We need to rebuild the spilt location expression and
+ // point the DBG_VALUE at the frame register.
+ DebugExpr = DIExpression::prepend(DebugInstr->getDebugExpression(),
+ DIExpression::ApplyOffset,
+ DiffIt.Loc.SpillLocation.SpillOffset);
+ Reg = TRI->getFrameRegister(*DebugInstr->getMF());
+ IsIndirect = true;
+ }
+
MI = BuildMI(MBB, MBB.instr_begin(), DebugInstr->getDebugLoc(),
- DebugInstr->getDesc(), DebugInstr->isIndirectDebugValue(),
- DebugInstr->getOperand(0).getReg(),
- DebugInstr->getDebugVariable(),
- DebugInstr->getDebugExpression());
- if (DebugInstr->isIndirectDebugValue())
- MI->getOperand(1).setImm(DebugInstr->getOperand(1).getImm());
+ DebugInstr->getDesc(), IsIndirect, Reg,
+ DebugInstr->getDebugVariable(), DebugExpr);
}
LLVM_DEBUG(dbgs() << "Inserted: "; MI->dump(););
ILS.set(ID);
Modified: llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir?rev=369092&r1=369091&r2=369092&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir (original)
+++ llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir Fri Aug 16 03:04:17 2019
@@ -2,6 +2,8 @@
# Generated from the following source with:
# clang -g -mllvm -stop-before=livedebugvalues -S -O2 test.c -o test.mir
+# Then more functions added to test for extra behaviours with complex
+# expressions.
# #define FORCE_SPILL() \
# __asm volatile("" : : : \
@@ -14,9 +16,10 @@
# return *(p + 1);
# }
-# Pick out DILocalVariable numbers for "p" and "q"
+# Pick out DILocalVariable numbers for "p", "q" and "r"
# CHECK: ![[PVAR:[0-9]+]] = !DILocalVariable(name: "p",
# CHECK: ![[QVAR:[0-9]+]] = !DILocalVariable(name: "q",
+# CHECK: ![[RVAR:[0-9]+]] = !DILocalVariable(name: "r",
# Ascertain that the spill has been recognized and manifested in a DBG_VALUE.
# CHECK: MOV64mr $rsp,{{.*-8.*}}killed{{.*}}$rdi :: (store 8 into %stack.0)
@@ -59,6 +62,23 @@
ret i32 %0, !dbg !128
}
+ define dso_local i32 @h(i32* readonly %p) local_unnamed_addr !dbg !207 {
+ entry:
+ call void @llvm.dbg.value(metadata i32* %p, metadata !213, metadata !DIExpression()), !dbg !214
+ %tobool = icmp eq i32* %p, null, !dbg !215
+ br i1 %tobool, label %if.end, label %if.then, !dbg !217
+
+ if.then: ; preds = %entry
+ tail call void asm sideeffect "", "~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"(), !dbg !218, !srcloc !220
+ br label %if.end, !dbg !221
+
+ if.end: ; preds = %entry, %if.then
+ %add.ptr = getelementptr inbounds i32, i32* %p, i64 1, !dbg !222
+ %0 = load i32, i32* %add.ptr, align 4, !dbg !223, !tbaa !24
+ ret i32 %0, !dbg !228
+ }
+
+
declare void @llvm.dbg.value(metadata, metadata, metadata)
!llvm.dbg.cu = !{!0}
@@ -95,7 +115,7 @@
!27 = !{!"Simple C/C++ TBAA"}
!28 = !DILocation(line: 9, column: 3, scope: !7)
!101 = !DIBasicType(name: "looong int", size: 64, encoding: DW_ATE_signed)
- !107 = distinct !DISubprogram(name: "g", scope: !1, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !112)
+ !107 = distinct !DISubprogram(name: "g", scope: !0, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !112)
!112 = !{!113}
!113 = !DILocalVariable(name: "q", arg: 1, scope: !107, file: !1, line: 105, type: !101)
!114 = !DILocation(line: 105, column: 12, scope: !107)
@@ -109,8 +129,21 @@
!122 = !DILocation(line: 109, column: 14, scope: !107)
!123 = !DILocation(line: 109, column: 10, scope: !107)
!128 = !DILocation(line: 109, column: 3, scope: !107)
-
-
+ !201 = !DIBasicType(name: "looong int", size: 64, encoding: DW_ATE_signed)
+ !207 = distinct !DISubprogram(name: "g", scope: !0, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !212)
+ !212 = !{!213}
+ !213 = !DILocalVariable(name: "r", arg: 1, scope: !207, file: !1, line: 105, type: !201)
+ !214 = !DILocation(line: 105, column: 12, scope: !207)
+ !215 = !DILocation(line: 106, column: 7, scope: !216)
+ !216 = distinct !DILexicalBlock(scope: !207, file: !1, line: 106, column: 7)
+ !217 = !DILocation(line: 106, column: 7, scope: !207)
+ !218 = !DILocation(line: 107, column: 5, scope: !219)
+ !219 = distinct !DILexicalBlock(scope: !216, file: !1, line: 106, column: 10)
+ !220 = !{i32 -2147471544}
+ !221 = !DILocation(line: 108, column: 3, scope: !219)
+ !222 = !DILocation(line: 109, column: 14, scope: !207)
+ !223 = !DILocation(line: 109, column: 10, scope: !207)
+ !228 = !DILocation(line: 109, column: 3, scope: !207)
...
---
name: f
@@ -298,3 +331,111 @@ body: |
RETQ $eax, debug-location !128
...
+---
+# This third function tests that complex expressions are spilt, and restored
+# correctly within a basic block.
+
+# FIXME: the spilt location below is wrong, there should be a deref between
+# the spill-offset and the DW_OP_plus_uconst.
+
+# CHECK-LABEL: name: h
+# CHECK-LABEL: bb.0.entry:
+# CHECK: DBG_VALUE $rdi, $noreg, ![[RVAR]], !DIExpression(DW_OP_plus_uconst, 1)
+# CHECK-LABEL: bb.1.if.then:
+# CHECK: DBG_VALUE $rdi, $noreg, ![[RVAR]], !DIExpression(DW_OP_plus_uconst, 1)
+# CHECK: DBG_VALUE $rsp, 0, ![[RVAR]], !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_plus_uconst, 1)
+# CHECK: DBG_VALUE $rdi, $noreg, ![[RVAR]], !DIExpression(DW_OP_plus_uconst, 1)
+# CHECK-LABEL: bb.2.if.end:
+# CHECK: DBG_VALUE $rdi, $noreg, ![[RVAR]], !DIExpression(DW_OP_plus_uconst, 1)
+
+name: h
+alignment: 4
+tracksRegLiveness: true
+liveins:
+ - { reg: '$rdi', virtual-reg: '' }
+frameInfo:
+ stackSize: 48
+ offsetAdjustment: -48
+ maxAlignment: 8
+ cvBytesOfCalleeSavedRegisters: 48
+ localFrameSize: 0
+fixedStack:
+ - { id: 0, type: spill-slot, offset: -56, size: 8, alignment: 8, stack-id: default,
+ callee-saved-register: '$rbx', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+ - { id: 1, type: spill-slot, offset: -48, size: 8, alignment: 16, stack-id: default,
+ callee-saved-register: '$r12', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+ - { id: 2, type: spill-slot, offset: -40, size: 8, alignment: 8, stack-id: default,
+ callee-saved-register: '$r13', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+ - { id: 3, type: spill-slot, offset: -32, size: 8, alignment: 16, stack-id: default,
+ callee-saved-register: '$r14', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+ - { id: 4, type: spill-slot, offset: -24, size: 8, alignment: 8, stack-id: default,
+ callee-saved-register: '$r15', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+ - { id: 5, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default,
+ callee-saved-register: '$rbp', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+stack:
+ - { id: 0, name: '', type: spill-slot, offset: -64, size: 8, alignment: 8,
+ stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+constants: []
+body: |
+ bb.0.entry:
+ successors: %bb.2(0x30000000), %bb.1(0x50000000)
+ liveins: $rdi, $rbx, $r12, $r13, $r14, $r15, $rbp
+
+ DBG_VALUE $rdi, $noreg, !213, !DIExpression(DW_OP_plus_uconst, 1), debug-location !214
+ TEST64rr renamable $rdi, renamable $rdi, implicit-def $eflags, debug-location !215
+ JCC_1 %bb.2, 4, implicit $eflags, debug-location !217
+
+ bb.1.if.then:
+ successors: %bb.2(0x80000000)
+ liveins: $rdi, $rbp, $r15, $r14, $r13, $r12, $rbx
+
+ frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 16
+ frame-setup PUSH64r killed $r15, implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 24
+ frame-setup PUSH64r killed $r14, implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 32
+ frame-setup PUSH64r killed $r13, implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 40
+ frame-setup PUSH64r killed $r12, implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 48
+ frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 56
+ CFI_INSTRUCTION offset $rbx, -56
+ CFI_INSTRUCTION offset $r12, -48
+ CFI_INSTRUCTION offset $r13, -40
+ CFI_INSTRUCTION offset $r14, -32
+ CFI_INSTRUCTION offset $r15, -24
+ CFI_INSTRUCTION offset $rbp, -16
+ MOV64mr $rsp, 1, $noreg, -8, $noreg, killed renamable $rdi :: (store 8 into %stack.0)
+ INLINEASM &"", 1, 12, implicit-def dead early-clobber $rax, 12, implicit-def dead early-clobber $rbx, 12, implicit-def dead early-clobber $rcx, 12, implicit-def dead early-clobber $rdx, 12, implicit-def dead early-clobber $rsi, 12, implicit-def dead early-clobber $rdi, 12, implicit-def dead early-clobber $rbp, 12, implicit-def dead early-clobber $r8, 12, implicit-def dead early-clobber $r9, 12, implicit-def dead early-clobber $r10, 12, implicit-def dead early-clobber $r11, 12, implicit-def dead early-clobber $r12, 12, implicit-def dead early-clobber $r13, 12, implicit-def dead early-clobber $r14, 12, implicit-def dead early-clobber $r15, 12, implicit-def dead early-clobber $eflags, !220, debug-location !218
+ renamable $rdi = MOV64rm $rsp, 1, $noreg, -8, $noreg :: (load 8 from %stack.0)
+ $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 48
+ $r12 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 40
+ $r13 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 32
+ $r14 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 24
+ $r15 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 16
+ $rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+ CFI_INSTRUCTION def_cfa_offset 8
+
+ bb.2.if.end:
+ liveins: $rdi, $rbx, $r12, $r13, $r14, $r15, $rbp
+
+ renamable $eax = MOV32rm killed renamable $rdi, 1, $noreg, 4, $noreg, debug-location !223 :: (load 4 from %ir.add.ptr, !tbaa !24)
+ RETQ $eax, debug-location !228
+
+
+
+...
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