[llvm] b2cf024 - [DebugInfo][CSInfo] Don't use clobbered registers as locations
Jeremy Morse via llvm-commits
llvm-commits at lists.llvm.org
Mon Jan 23 04:21:18 PST 2023
Author: Jeremy Morse
Date: 2023-01-23T12:20:10Z
New Revision: b2cf024280b30692ac3e4720eb7c541e6ef7449f
URL: https://github.com/llvm/llvm-project/commit/b2cf024280b30692ac3e4720eb7c541e6ef7449f
DIFF: https://github.com/llvm/llvm-project/commit/b2cf024280b30692ac3e4720eb7c541e6ef7449f.diff
LOG: [DebugInfo][CSInfo] Don't use clobbered registers as locations
When finding call-site argument locations, don't consider registers to be
location candidates if they will be clobbered between the copy to/from them
and call site. Doing so would present overwritten register values as entry
values in called functions.
This patch adds a collection of register units defined as we walk back from
the call site, and prevents the acceptance of a call-site parameter
location if it will be clobbered on that path.
Fixes https://github.com/llvm/llvm-project/issues/57444
Differential Revision: https://reviews.llvm.org/D141279
Added:
llvm/test/DebugInfo/MIR/X86/dbgcall-site-clobbered-regs.mir
Modified:
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index d577af912f6a1..cde790cc77fbe 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -597,6 +597,9 @@ struct FwdRegParamInfo {
/// Register worklist for finding call site values.
using FwdRegWorklist = MapVector<unsigned, SmallVector<FwdRegParamInfo, 2>>;
+/// Container for the set of registers known to be clobbered on the path to a
+/// call site.
+using ClobberedRegSet = SmallSet<Register, 16>;
/// Append the expression \p Addition to \p Original and return the result.
static const DIExpression *combineDIExpressions(const DIExpression *Original,
@@ -668,7 +671,8 @@ static void addToFwdRegWorklist(FwdRegWorklist &Worklist, unsigned Reg,
/// Interpret values loaded into registers by \p CurMI.
static void interpretValues(const MachineInstr *CurMI,
FwdRegWorklist &ForwardedRegWorklist,
- ParamSet &Params) {
+ ParamSet &Params,
+ ClobberedRegSet &ClobberedRegUnits) {
const MachineFunction *MF = CurMI->getMF();
const DIExpression *EmptyExpr =
@@ -700,6 +704,7 @@ static void interpretValues(const MachineInstr *CurMI,
// If the MI is an instruction defining one or more parameters' forwarding
// registers, add those defines.
+ ClobberedRegSet NewClobberedRegUnits;
auto getForwardingRegsDefinedByMI = [&](const MachineInstr &MI,
SmallSetVector<unsigned, 4> &Defs) {
if (MI.isDebugInstr())
@@ -710,6 +715,8 @@ static void interpretValues(const MachineInstr *CurMI,
for (auto &FwdReg : ForwardedRegWorklist)
if (TRI.regsOverlap(FwdReg.first, MO.getReg()))
Defs.insert(FwdReg.first);
+ for (MCRegUnitIterator Units(MO.getReg(), &TRI); Units.isValid(); ++Units)
+ NewClobberedRegUnits.insert(*Units);
}
}
};
@@ -718,8 +725,22 @@ static void interpretValues(const MachineInstr *CurMI,
SmallSetVector<unsigned, 4> FwdRegDefs;
getForwardingRegsDefinedByMI(*CurMI, FwdRegDefs);
- if (FwdRegDefs.empty())
+ if (FwdRegDefs.empty()) {
+ // Any definitions by this instruction will clobber earlier reg movements.
+ ClobberedRegUnits.insert(NewClobberedRegUnits.begin(),
+ NewClobberedRegUnits.end());
return;
+ }
+
+ // It's possible that we find a copy from a non-volatile register to the param
+ // register, which is clobbered in the meantime. Test for clobbered reg unit
+ // overlaps before completing.
+ auto IsRegClobberedInMeantime = [&](Register Reg) -> bool {
+ for (auto &RegUnit : ClobberedRegUnits)
+ if (TRI.hasRegUnit(Reg, RegUnit))
+ return true;
+ return false;
+ };
for (auto ParamFwdReg : FwdRegDefs) {
if (auto ParamValue = TII.describeLoadedValue(*CurMI, ParamFwdReg)) {
@@ -732,7 +753,8 @@ static void interpretValues(const MachineInstr *CurMI,
Register SP = TLI.getStackPointerRegisterToSaveRestore();
Register FP = TRI.getFrameRegister(*MF);
bool IsSPorFP = (RegLoc == SP) || (RegLoc == FP);
- if (TRI.isCalleeSavedPhysReg(RegLoc, *MF) || IsSPorFP) {
+ if (!IsRegClobberedInMeantime(RegLoc) &&
+ (TRI.isCalleeSavedPhysReg(RegLoc, *MF) || IsSPorFP)) {
MachineLocation MLoc(RegLoc, /*Indirect=*/IsSPorFP);
finishCallSiteParams(MLoc, ParamValue->second,
ForwardedRegWorklist[ParamFwdReg], Params);
@@ -754,6 +776,10 @@ static void interpretValues(const MachineInstr *CurMI,
for (auto ParamFwdReg : FwdRegDefs)
ForwardedRegWorklist.erase(ParamFwdReg);
+ // Any definitions by this instruction will clobber earlier reg movements.
+ ClobberedRegUnits.insert(NewClobberedRegUnits.begin(),
+ NewClobberedRegUnits.end());
+
// Now that we are done handling this instruction, add items from the
// temporary worklist to the real one.
for (auto &New : TmpWorklistItems)
@@ -763,7 +789,8 @@ static void interpretValues(const MachineInstr *CurMI,
static bool interpretNextInstr(const MachineInstr *CurMI,
FwdRegWorklist &ForwardedRegWorklist,
- ParamSet &Params) {
+ ParamSet &Params,
+ ClobberedRegSet &ClobberedRegUnits) {
// Skip bundle headers.
if (CurMI->isBundle())
return true;
@@ -781,7 +808,7 @@ static bool interpretNextInstr(const MachineInstr *CurMI,
if (CurMI->getNumOperands() == 0)
return true;
- interpretValues(CurMI, ForwardedRegWorklist, Params);
+ interpretValues(CurMI, ForwardedRegWorklist, Params, ClobberedRegUnits);
return true;
}
@@ -833,6 +860,7 @@ static void collectCallSiteParameters(const MachineInstr *CallMI,
bool ShouldTryEmitEntryVals = MBB->getIterator() == MF->begin();
// Search for a loading value in forwarding registers inside call delay slot.
+ ClobberedRegSet ClobberedRegUnits;
if (CallMI->hasDelaySlot()) {
auto Suc = std::next(CallMI->getIterator());
// Only one-instruction delay slot is supported.
@@ -841,14 +869,14 @@ static void collectCallSiteParameters(const MachineInstr *CallMI,
assert(std::next(Suc) == BundleEnd &&
"More than one instruction in call delay slot");
// Try to interpret value loaded by instruction.
- if (!interpretNextInstr(&*Suc, ForwardedRegWorklist, Params))
+ if (!interpretNextInstr(&*Suc, ForwardedRegWorklist, Params, ClobberedRegUnits))
return;
}
// Search for a loading value in forwarding registers.
for (; I != MBB->rend(); ++I) {
// Try to interpret values loaded by instruction.
- if (!interpretNextInstr(&*I, ForwardedRegWorklist, Params))
+ if (!interpretNextInstr(&*I, ForwardedRegWorklist, Params, ClobberedRegUnits))
return;
}
diff --git a/llvm/test/DebugInfo/MIR/X86/dbgcall-site-clobbered-regs.mir b/llvm/test/DebugInfo/MIR/X86/dbgcall-site-clobbered-regs.mir
new file mode 100644
index 0000000000000..71e177095b868
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/X86/dbgcall-site-clobbered-regs.mir
@@ -0,0 +1,158 @@
+# RUN: llc %s -o - -filetype=obj -start-after=livedebugvalues \
+# RUN: -emit-call-site-info | \
+# RUN: llvm-dwarfdump - | FileCheck %s --implicit-check-not=call_value
+#
+## Test that call-site information is produced for this input, but use the
+## implicit not above to check that no call value entries are produced for
+## the tail call. They're clobbered by the restoration of r14 and rbx.
+##
+## Addresses https://github.com/llvm/llvm-project/issues/57444
+#
+# CHECK: DW_TAG_call_site
+# CHECK-NEXT: DW_AT_call_origin
+# CHECK-NEXT: DW_AT_call_return_pc
+#
+# CHECK: DW_TAG_call_site
+# CHECK-NEXT: DW_AT_call_origin
+# CHECK-NEXT: DW_AT_call_tail_call (true)
+# CHECK-NEXT: DW_AT_call_pc
+
+--- |
+ ; ModuleID = 'out.ll'
+ source_filename = "test.c"
+ target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+ target triple = "x86_64-unknown-linux-gnu"
+
+ @str = private unnamed_addr constant [5 x i8] c"ohai\00", align 1
+
+ ; Function Attrs: nounwind uwtable
+ define dso_local i32 @foo(i64 noundef %a, i64 noundef %b) local_unnamed_addr #0 !dbg !16 {
+ entry:
+ call void @llvm.dbg.value(metadata i64 %a, metadata !22, metadata !DIExpression()), !dbg !24
+ call void @llvm.dbg.value(metadata i64 %b, metadata !23, metadata !DIExpression()), !dbg !24
+ %call = tail call i32 (...) @baz() #5, !dbg !25
+ %conv = trunc i64 %a to i32, !dbg !26
+ %conv1 = trunc i64 %b to i32, !dbg !27
+ %call2 = tail call i32 @bar(i32 noundef %conv, i32 noundef %conv1) #5, !dbg !28
+ ret i32 %call2, !dbg !29
+ }
+
+ declare !dbg !30 i32 @baz(...) local_unnamed_addr #1
+
+ declare !dbg !34 i32 @bar(i32 noundef, i32 noundef) local_unnamed_addr #1
+
+ ; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
+ declare void @llvm.dbg.value(metadata, metadata, metadata) #3
+
+ !llvm.dbg.cu = !{!0}
+ !llvm.module.flags = !{!9, !10, !11, !12, !13, !14}
+ !llvm.ident = !{!15}
+
+ !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !2, splitDebugInlining: false, nameTableKind: None)
+ !1 = !DIFile(filename: "test.c", directory: ".", checksumkind: CSK_MD5, checksum: "98e51a9cf3bc6e1c3cc216ca4c82353a")
+ !2 = !{!3}
+ !3 = !DIGlobalVariableExpression(var: !4, expr: !DIExpression())
+ !4 = distinct !DIGlobalVariable(scope: null, file: !1, line: 11, type: !5, isLocal: true, isDefinition: true)
+ !5 = !DICompositeType(tag: DW_TAG_array_type, baseType: !6, size: 48, elements: !7)
+ !6 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+ !7 = !{!8}
+ !8 = !DISubrange(count: 6)
+ !9 = !{i32 7, !"Dwarf Version", i32 5}
+ !10 = !{i32 2, !"Debug Info Version", i32 3}
+ !11 = !{i32 1, !"wchar_size", i32 4}
+ !12 = !{i32 8, !"PIC Level", i32 2}
+ !13 = !{i32 7, !"PIE Level", i32 2}
+ !14 = !{i32 7, !"uwtable", i32 2}
+ !15 = !{!"clang"}
+ !16 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 5, type: !17, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !21)
+ !17 = !DISubroutineType(types: !18)
+ !18 = !{!19, !20, !20}
+ !19 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+ !20 = !DIBasicType(name: "long", size: 64, encoding: DW_ATE_signed)
+ !21 = !{!22, !23}
+ !22 = !DILocalVariable(name: "a", arg: 1, scope: !16, file: !1, line: 5, type: !20)
+ !23 = !DILocalVariable(name: "b", arg: 2, scope: !16, file: !1, line: 5, type: !20)
+ !24 = !DILocation(line: 0, scope: !16)
+ !25 = !DILocation(line: 6, column: 3, scope: !16)
+ !26 = !DILocation(line: 7, column: 14, scope: !16)
+ !27 = !DILocation(line: 7, column: 17, scope: !16)
+ !28 = !DILocation(line: 7, column: 10, scope: !16)
+ !29 = !DILocation(line: 7, column: 3, scope: !16)
+ !30 = !DISubprogram(name: "baz", scope: !1, file: !1, line: 4, type: !31, spFlags: DISPFlagOptimized, retainedNodes: !33)
+ !31 = !DISubroutineType(types: !32)
+ !32 = !{!19}
+ !33 = !{}
+ !34 = !DISubprogram(name: "bar", scope: !1, file: !1, line: 3, type: !35, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !33)
+ !35 = !DISubroutineType(types: !36)
+ !36 = !{!19, !19, !19}
+ !37 = distinct !DISubprogram(name: "qux", scope: !1, file: !1, line: 10, type: !31, scopeLine: 10, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !33)
+ !38 = !DILocation(line: 11, column: 3, scope: !37)
+ !39 = !DILocation(line: 12, column: 3, scope: !37)
+
+...
+---
+name: foo
+alignment: 16
+tracksRegLiveness: true
+tracksDebugUserValues: true
+liveins:
+ - { reg: '$rdi' }
+ - { reg: '$rsi' }
+frameInfo:
+ stackSize: 24
+ offsetAdjustment: -24
+ maxAlignment: 1
+ adjustsStack: true
+ hasCalls: true
+ maxCallFrameSize: 0
+ cvBytesOfCalleeSavedRegisters: 16
+ hasTailCall: true
+fixedStack:
+ - { id: 0, type: spill-slot, offset: -24, size: 8, alignment: 8, callee-saved-register: '$rbx' }
+ - { id: 1, type: spill-slot, offset: -16, size: 8, alignment: 16, callee-saved-register: '$r14' }
+callSites:
+ - { bb: 0, offset: 15 }
+ - { bb: 0, offset: 28, fwdArgRegs:
+ - { arg: 0, reg: '$edi' }
+ - { arg: 1, reg: '$esi' } }
+debugValueSubstitutions:
+ - { srcinst: 2, srcop: 0, dstinst: 1, dstop: 0, subreg: 6 }
+ - { srcinst: 4, srcop: 0, dstinst: 3, dstop: 0, subreg: 6 }
+machineFunctionInfo: {}
+body: |
+ bb.0.entry:
+ liveins: $rdi, $rsi, $r14, $rbx
+
+ DBG_VALUE $rdi, $noreg, !22, !DIExpression(), debug-location !24
+ DBG_VALUE $rsi, $noreg, !23, !DIExpression(), debug-location !24
+ frame-setup PUSH64r killed $r14, implicit-def $rsp, implicit $rsp
+ frame-setup CFI_INSTRUCTION def_cfa_offset 16
+ frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp
+ frame-setup CFI_INSTRUCTION def_cfa_offset 24
+ frame-setup PUSH64r undef $rax, implicit-def $rsp, implicit $rsp
+ frame-setup CFI_INSTRUCTION def_cfa_offset 32
+ CFI_INSTRUCTION offset $rbx, -24
+ CFI_INSTRUCTION offset $r14, -16
+ DBG_PHI $rsi, 3
+ DBG_PHI $rdi, 1
+ $rbx = MOV64rr $rsi
+ $r14 = MOV64rr $rdi
+ dead $eax = XOR32rr undef $eax, undef $eax, implicit-def dead $eflags, implicit-def $al, debug-location !25
+ CALL64pcrel32 target-flags(x86-plt) @baz, csr_64, implicit $rsp, implicit $ssp, implicit killed $al, implicit-def $rsp, implicit-def $ssp, implicit-def dead $eax, debug-location !25
+ DBG_VALUE $rbx, $noreg, !23, !DIExpression(), debug-location !24
+ DBG_VALUE $r14, $noreg, !22, !DIExpression(), debug-location !24
+ $edi = MOV32rr $r14d, implicit killed $r14, debug-location !28
+ $esi = MOV32rr $ebx, implicit killed $rbx, debug-location !28
+ $rsp = frame-destroy ADD64ri8 $rsp, 8, implicit-def dead $eflags, debug-location !28
+ frame-destroy CFI_INSTRUCTION def_cfa_offset 24, debug-location !28
+ ;; This tail-call popping of rbx clobbers the call site information
+ $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !28
+ DBG_VALUE $rsi, $noreg, !23, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location !24
+ frame-destroy CFI_INSTRUCTION def_cfa_offset 16, debug-location !28
+ ;; This tail-call popping of r14 clobbers the call site information
+ $r14 = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !28
+ DBG_VALUE $rdi, $noreg, !22, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location !24
+ frame-destroy CFI_INSTRUCTION def_cfa_offset 8, debug-location !28
+ TAILJMPd64 target-flags(x86-plt) @bar, csr_64, implicit $rsp, implicit $ssp, implicit $rsp, implicit $ssp, implicit $edi, implicit $esi, debug-location !28
+
+...
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