[llvm] d966bf8 - [WebAssembly] Preserve debug frame base information through register coloring
Derek Schuff via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 28 16:59:24 PST 2020
Author: Derek Schuff
Date: 2020-01-28T16:58:15-08:00
New Revision: d966bf830fe1625e0037e8b59e918f1c49ace3f3
URL: https://github.com/llvm/llvm-project/commit/d966bf830fe1625e0037e8b59e918f1c49ace3f3
DIFF: https://github.com/llvm/llvm-project/commit/d966bf830fe1625e0037e8b59e918f1c49ace3f3.diff
LOG: [WebAssembly] Preserve debug frame base information through register coloring
2 fixes:
Register coloring can re-assign virtual registers. When the frame base register
is colored, update the DwarfFrameBase accordingly When the frame base register
is stackified, do not attempt to encode DW_AT_frame_base as a local In the
future we will presumably want to handle this case better but for now we can
emit worse debug info rather than crashing.
Differential Revision: https://reviews.llvm.org/D73581
Added:
llvm/test/CodeGen/WebAssembly/debugtest-opt.ll
Modified:
llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
index 1196b5dd63d0..6ca711394380 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
@@ -77,8 +77,13 @@ static unsigned getLocalId(DenseMap<unsigned, unsigned> &Reg2Local,
auto P = Reg2Local.insert(std::make_pair(Reg, CurLocal));
if (P.second) {
// Mark the local allocated for the frame base vreg.
- if (MFI.isFrameBaseVirtual() && Reg == MFI.getFrameBaseVreg())
+ if (MFI.isFrameBaseVirtual() && Reg == MFI.getFrameBaseVreg()) {
+ LLVM_DEBUG({
+ dbgs() << "Allocating local " << CurLocal << "for VReg "
+ << Register::virtReg2Index(Reg) << '\n';
+ });
MFI.setFrameBaseLocal(CurLocal);
+ }
++CurLocal;
}
return P.first->second;
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
index 9da7f53fe106..21b81d8cd0ed 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
@@ -266,7 +266,7 @@ WebAssemblyFrameLowering::getDwarfFrameBase(const MachineFunction &MF) const {
DwarfFrameBase Loc;
Loc.Kind = DwarfFrameBase::WasmFrameBase;
const WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
- if (needsSP(MF)) {
+ if (needsSP(MF) && MFI.isFrameBaseVirtual()) {
unsigned LocalNum = MFI.getFrameBaseLocal();
Loc.Location.WasmLoc = {WebAssembly::TI_LOCAL_START, LocalNum};
} else {
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
index f2bbdb81033f..312e1ee9d687 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
@@ -101,6 +101,7 @@ class WebAssemblyFunctionInfo final : public MachineFunctionInfo {
assert(FrameBaseVreg != -1U && "Frame base vreg hasn't been set");
return FrameBaseVreg;
}
+ void clearFrameBaseVreg() { FrameBaseVreg = -1U; }
// Return true if the frame base physreg has been replaced by a virtual reg.
bool isFrameBaseVirtual() const { return FrameBaseVreg != -1U; }
void setFrameBaseLocal(unsigned Local) { FrameBaseLocal = Local; }
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
index 043b6f1b7d18..20fe2b2b7bfc 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
@@ -157,6 +157,9 @@ bool WebAssemblyRegColoring::runOnMachineFunction(MachineFunction &MF) {
Changed |= Old != New;
UsedColors.set(Color);
Assignments[Color].push_back(LI);
+ // If we reassigned the stack pointer, update the debug frame base info.
+ if (Old != New && MFI.isFrameBaseVirtual() && MFI.getFrameBaseVreg() == Old)
+ MFI.setFrameBaseVreg(New);
LLVM_DEBUG(dbgs() << "Assigning vreg" << Register::virtReg2Index(LI->reg)
<< " to vreg" << Register::virtReg2Index(New) << "\n");
}
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
index 58082bb8c5f9..e49034467f73 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
@@ -857,6 +857,12 @@ bool WebAssemblyRegStackify::runOnMachineFunction(MachineFunction &MF) {
!TreeWalker.isOnStack(Reg);
if (CanMove && hasOneUse(Reg, Def, MRI, MDT, LIS)) {
Insert = moveForSingleUse(Reg, Op, Def, MBB, Insert, LIS, MFI, MRI);
+
+ // If we are removing the frame base reg completely, remove the debug
+ // info as well.
+ // TODO: Encode this properly as a stackified value.
+ if (MFI.isFrameBaseVirtual() && MFI.getFrameBaseVreg() == Reg)
+ MFI.clearFrameBaseVreg();
} else if (shouldRematerialize(*Def, AA, TII)) {
Insert =
rematerializeCheapDef(Reg, Op, *Def, MBB, Insert->getIterator(),
diff --git a/llvm/test/CodeGen/WebAssembly/debugtest-opt.ll b/llvm/test/CodeGen/WebAssembly/debugtest-opt.ll
new file mode 100644
index 000000000000..43dc2c2dfadf
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/debugtest-opt.ll
@@ -0,0 +1,72 @@
+; RUN: llc < %s -filetype=obj -o - | llvm-dwarfdump -
+
+; To regenerate this file, use approximately the following C code:
+; int* globl;
+; void baz(int arg) {
+; int locl;
+; globl = &locl;
+; }
+
+; CHECK: DW_TAG_subprogram
+; CHECK-NEXT: DW_AT_low_pc
+; CHECK-NEXT: DW_AT_high_pc
+;; Check that we fall back to the default frame base (the global)
+; CHECK-NEXT: DW_AT_frame_base (DW_OP_WASM_location 0x1 +0, DW_OP_stack_value)
+
+; TODO: Find a more-reduced test case for The fix in WebAssemblyRegColoring
+
+; ModuleID = 'debugtest-opt.c'
+source_filename = "debugtest-opt.c"
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32"
+
+ at globl = hidden local_unnamed_addr global i32* null, align 4, !dbg !0
+
+; Function Attrs: nounwind writeonly
+define hidden void @baz(i32 %arg) local_unnamed_addr #0 !dbg !12 {
+entry:
+ %locl = alloca i32, align 4
+ call void @llvm.dbg.value(metadata i32 %arg, metadata !16, metadata !DIExpression()), !dbg !18
+ %0 = bitcast i32* %locl to i8*, !dbg !19
+ store i32* %locl, i32** @globl, align 4, !dbg !20, !tbaa !21
+ ret void, !dbg !25
+}
+
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+
+attributes #0 = { nounwind writeonly "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind willreturn }
+attributes #2 = { nounwind readnone speculatable willreturn }
+attributes #3 = { nounwind }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!8, !9, !10}
+!llvm.ident = !{!11}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "globl", scope: !2, file: !3, line: 2, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 11.0.0 (https://github.com/llvm/llvm-project.git ee80f8bef31e0f98c9a0e1d79dc5f1ff51ed9e3a)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
+!3 = !DIFile(filename: "debugtest-opt.c", directory: "/s/llvm-upstream")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !7, size: 32)
+!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!8 = !{i32 7, !"Dwarf Version", i32 4}
+!9 = !{i32 2, !"Debug Info Version", i32 3}
+!10 = !{i32 1, !"wchar_size", i32 4}
+!11 = !{!"clang version 11.0.0 (https://github.com/llvm/llvm-project.git ee80f8bef31e0f98c9a0e1d79dc5f1ff51ed9e3a)"}
+!12 = distinct !DISubprogram(name: "baz", scope: !3, file: !3, line: 14, type: !13, scopeLine: 14, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !15)
+!13 = !DISubroutineType(types: !14)
+!14 = !{null, !7}
+!15 = !{!16, !17}
+!16 = !DILocalVariable(name: "arg", arg: 1, scope: !12, file: !3, line: 14, type: !7)
+!17 = !DILocalVariable(name: "locl", scope: !12, file: !3, line: 15, type: !7)
+!18 = !DILocation(line: 0, scope: !12)
+!19 = !DILocation(line: 15, column: 3, scope: !12)
+!20 = !DILocation(line: 16, column: 9, scope: !12)
+!21 = !{!22, !22, i64 0}
+!22 = !{!"any pointer", !23, i64 0}
+!23 = !{!"omnipotent char", !24, i64 0}
+!24 = !{!"Simple C/C++ TBAA"}
+!25 = !DILocation(line: 17, column: 1, scope: !12)
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