[llvm][x64] Mark win x64 SEH pseudo instruction as meta instructions (again) #112962
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…#110889) When adding new SEH pseudo instructions in llvm#110024 I noticed that some of the tests were changing their output since these new instructions were counting towards thresholds for branching versus folding decisions. These instructions do not result in real machine instructions being emitted, so they should be marked as meta instructions.
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@llvm/pr-subscribers-backend-x86 Author: Daniel Paoliello (dpaoliello) ChangesWhen adding new SEH pseudo instructions in #110024 I noticed that some of the tests were changing their output since these new instructions were counting towards thresholds for branching versus folding decisions. These instructions do not result in real machine instructions being emitted, so they should be marked as meta instructions. This is a re-do of #110889 as we hit an issue where some of the SEH pseudo instructions in the prolog were being duplicated, which resulted errors being raised as the CodeView generator was seeing prolog directives after an end-prolog directive: <#110889 (comment)>. The fix for this is to mark the prolog related SEH pseudo instructions as being non-duplicatable. Full diff: https://github.com/llvm/llvm-project/pull/112962.diff 3 Files Affected:
diff --git a/llvm/lib/Target/X86/X86InstrCompiler.td b/llvm/lib/Target/X86/X86InstrCompiler.td
index 5a8177e2b3607b..a05c3f028442c0 100644
--- a/llvm/lib/Target/X86/X86InstrCompiler.td
+++ b/llvm/lib/Target/X86/X86InstrCompiler.td
@@ -235,7 +235,13 @@ let isBranch = 1, isTerminator = 1, isCodeGenOnly = 1 in {
//===----------------------------------------------------------------------===//
// Pseudo instructions used by unwind info.
//
-let isPseudo = 1, SchedRW = [WriteSystem] in {
+
+// Prolog instructions should not be duplicated, since this can cause issues
+// because 1) if only some of the instructions are duplicated, then we will
+// observe prolog instructions after the end-prolog instruction and 2) Windows
+// expects there to only be a single prolog (e.g., when checking if unwinding
+// is happening in the middle of a prolog).
+let isPseudo = 1, isMeta = 1, isNotDuplicable = 1, SchedRW = [WriteSystem] in {
def SEH_PushReg : I<0, Pseudo, (outs), (ins i32imm:$reg),
"#SEH_PushReg $reg", []>;
def SEH_SaveReg : I<0, Pseudo, (outs), (ins i32imm:$reg, i32imm:$dst),
@@ -252,6 +258,10 @@ let isPseudo = 1, SchedRW = [WriteSystem] in {
"#SEH_PushFrame $mode", []>;
def SEH_EndPrologue : I<0, Pseudo, (outs), (ins),
"#SEH_EndPrologue", []>;
+}
+
+// Epilog instructions:
+let isPseudo = 1, isMeta = 1, SchedRW = [WriteSystem] in {
def SEH_Epilogue : I<0, Pseudo, (outs), (ins),
"#SEH_Epilogue", []>;
}
diff --git a/llvm/test/CodeGen/X86/no-dup-cv-directive.ll b/llvm/test/CodeGen/X86/no-dup-cv-directive.ll
new file mode 100644
index 00000000000000..98ee9cff10d1c4
--- /dev/null
+++ b/llvm/test/CodeGen/X86/no-dup-cv-directive.ll
@@ -0,0 +1,119 @@
+; RUN: llc -O3 < %s | FileCheck %s
+
+; Regression test for https://github.com/llvm/llvm-project/pull/110889#issuecomment-2393405613
+; Marking x64 SEH instructions as meta led to cv directives being duplicated, which caused
+; `cv_fpo_stackalloc` to be observed after seeing a `cv_fpo_endprologue`, which is an error.
+
+; Generated from the following code:
+; int q;
+; class b {
+; public:
+; b();
+; };
+; struct G {
+; char n[sizeof(void *)];
+; int *i;
+; int p() const { return n[0] ? *i : 1; }
+; int s() const;
+; };
+; int G::s() const {
+; q = p();
+; b();
+; }
+; To reproduce: clang -target i686-w64-mingw32 -w -c repro.cpp -O3 -g -gcodeview -emit-llvm
+
+; CHECK-LABEL: __ZNK1G1sEv:
+; CHECK: .cv_fpo_proc __ZNK1G1sEv 0
+; CHECK: .cv_fpo_stackalloc 4
+; CHECK: .cv_fpo_endprologue
+; CHECK-NOT: .cv_fpo_stackalloc
+; CHECK-NOT: .cv_fpo_endprologue
+
+target datalayout = "e-m:x-p:32:32-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i686-w64-windows-gnu"
+
+%class.b = type { i8 }
+
+@q = dso_local local_unnamed_addr global i32 0, align 4, !dbg !0
+
+; Function Attrs: mustprogress noreturn
+define dso_local x86_thiscallcc noundef i32 @_ZNK1G1sEv(ptr nocapture noundef nonnull readonly align 4 dereferenceable(8) %this) local_unnamed_addr #0 align 2 !dbg !13 {
+entry:
+ %agg.tmp.ensured = alloca %class.b, align 1
+ #dbg_value(ptr %this, !30, !DIExpression(), !32)
+ #dbg_value(ptr %this, !33, !DIExpression(), !36)
+ %0 = load i8, ptr %this, align 4, !dbg !38, !tbaa !39
+ %tobool.not.i = icmp eq i8 %0, 0, !dbg !38
+ br i1 %tobool.not.i, label %_ZNK1G1pEv.exit, label %cond.true.i, !dbg !38
+
+cond.true.i: ; preds = %entry
+ %i.i = getelementptr inbounds nuw i8, ptr %this, i32 4, !dbg !38
+ %1 = load ptr, ptr %i.i, align 4, !dbg !38, !tbaa !42
+ %2 = load i32, ptr %1, align 4, !dbg !38, !tbaa !45
+ br label %_ZNK1G1pEv.exit, !dbg !38
+
+_ZNK1G1pEv.exit: ; preds = %entry, %cond.true.i
+ %cond.i = phi i32 [ %2, %cond.true.i ], [ 1, %entry ], !dbg !38
+ store i32 %cond.i, ptr @q, align 4, !dbg !47, !tbaa !45
+ call x86_thiscallcc void @_ZN1bC1Ev(ptr noundef nonnull align 1 dereferenceable(1) %agg.tmp.ensured), !dbg !48
+ unreachable, !dbg !48
+}
+
+declare dso_local x86_thiscallcc void @_ZN1bC1Ev(ptr noundef nonnull align 1 dereferenceable(1)) unnamed_addr #1
+
+attributes #0 = { mustprogress noreturn "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="pentium4" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+attributes #1 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="pentium4" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!6, !7, !8, !9, !10, !11}
+!llvm.ident = !{!12}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "q", scope: !2, file: !3, line: 1, type: !5, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !3, producer: "clang version 20.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !4, splitDebugInlining: false, nameTableKind: None)
+!3 = !DIFile(filename: "repro.cpp", directory: "C:\\llvm", checksumkind: CSK_MD5, checksum: "54362b0cc0bf4b9927aafc8b00498049")
+!4 = !{!0}
+!5 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!6 = !{i32 1, !"NumRegisterParameters", i32 0}
+!7 = !{i32 2, !"CodeView", i32 1}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 2}
+!10 = !{i32 1, !"MaxTLSAlign", i32 65536}
+!11 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+!12 = !{!"clang version 20.0.0"}
+!13 = distinct !DISubprogram(name: "s", linkageName: "_ZNK1G1sEv", scope: !14, file: !3, line: 12, type: !24, scopeLine: 12, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, declaration: !28, retainedNodes: !29)
+!14 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "G", file: !3, line: 6, size: 64, flags: DIFlagTypePassByValue, elements: !15, identifier: "_ZTS1G")
+!15 = !{!16, !21, !23, !28}
+!16 = !DIDerivedType(tag: DW_TAG_member, name: "n", scope: !14, file: !3, line: 7, baseType: !17, size: 32)
+!17 = !DICompositeType(tag: DW_TAG_array_type, baseType: !18, size: 32, elements: !19)
+!18 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!19 = !{!20}
+!20 = !DISubrange(count: 4)
+!21 = !DIDerivedType(tag: DW_TAG_member, name: "i", scope: !14, file: !3, line: 8, baseType: !22, size: 32, offset: 32)
+!22 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 32)
+!23 = !DISubprogram(name: "p", linkageName: "_ZNK1G1pEv", scope: !14, file: !3, line: 9, type: !24, scopeLine: 9, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
+!24 = !DISubroutineType(cc: DW_CC_BORLAND_thiscall, types: !25)
+!25 = !{!5, !26}
+!26 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !27, size: 32, flags: DIFlagArtificial | DIFlagObjectPointer)
+!27 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !14)
+!28 = !DISubprogram(name: "s", linkageName: "_ZNK1G1sEv", scope: !14, file: !3, line: 10, type: !24, scopeLine: 10, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
+!29 = !{!30}
+!30 = !DILocalVariable(name: "this", arg: 1, scope: !13, type: !31, flags: DIFlagArtificial | DIFlagObjectPointer)
+!31 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !27, size: 32)
+!32 = !DILocation(line: 0, scope: !13)
+!33 = !DILocalVariable(name: "this", arg: 1, scope: !34, type: !31, flags: DIFlagArtificial | DIFlagObjectPointer)
+!34 = distinct !DISubprogram(name: "p", linkageName: "_ZNK1G1pEv", scope: !14, file: !3, line: 9, type: !24, scopeLine: 9, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, declaration: !23, retainedNodes: !35)
+!35 = !{!33}
+!36 = !DILocation(line: 0, scope: !34, inlinedAt: !37)
+!37 = distinct !DILocation(line: 13, scope: !13)
+!38 = !DILocation(line: 9, scope: !34, inlinedAt: !37)
+!39 = !{!40, !40, i64 0}
+!40 = !{!"omnipotent char", !41, i64 0}
+!41 = !{!"Simple C++ TBAA"}
+!42 = !{!43, !44, i64 4}
+!43 = !{!"_ZTS1G", !40, i64 0, !44, i64 4}
+!44 = !{!"any pointer", !40, i64 0}
+!45 = !{!46, !46, i64 0}
+!46 = !{!"int", !40, i64 0}
+!47 = !DILocation(line: 13, scope: !13)
+!48 = !DILocation(line: 14, scope: !13)
diff --git a/llvm/test/CodeGen/X86/x86-win64-shrink-wrapping.ll b/llvm/test/CodeGen/X86/x86-win64-shrink-wrapping.ll
index d52990e753d3eb..8309593896bf0a 100644
--- a/llvm/test/CodeGen/X86/x86-win64-shrink-wrapping.ll
+++ b/llvm/test/CodeGen/X86/x86-win64-shrink-wrapping.ll
@@ -17,7 +17,7 @@ define i32 @loopInfoSaveOutsideLoop(i32 %cond, i32 %N) #0 {
; ENABLE-NEXT: .seh_pushreg %rbx
; ENABLE-NEXT: .seh_endprologue
; ENABLE-NEXT: testl %ecx, %ecx
-; ENABLE-NEXT: je .LBB0_4
+; ENABLE-NEXT: je .LBB0_5
; ENABLE-NEXT: # %bb.1: # %for.preheader
; ENABLE-NEXT: #APP
; ENABLE-NEXT: nop
@@ -38,11 +38,11 @@ define i32 @loopInfoSaveOutsideLoop(i32 %cond, i32 %N) #0 {
; ENABLE-NEXT: nop
; ENABLE-NEXT: #NO_APP
; ENABLE-NEXT: shll $3, %eax
-; ENABLE-NEXT: jmp .LBB0_5
-; ENABLE-NEXT: .LBB0_4: # %if.else
+; ENABLE-NEXT: popq %rbx
+; ENABLE-NEXT: retq
+; ENABLE-NEXT: .LBB0_5: # %if.else
; ENABLE-NEXT: movl %edx, %eax
; ENABLE-NEXT: addl %edx, %eax
-; ENABLE-NEXT: .LBB0_5: # %if.end
; ENABLE-NEXT: popq %rbx
; ENABLE-NEXT: retq
; ENABLE-NEXT: .seh_endproc
@@ -53,7 +53,7 @@ define i32 @loopInfoSaveOutsideLoop(i32 %cond, i32 %N) #0 {
; DISABLE-NEXT: .seh_pushreg %rbx
; DISABLE-NEXT: .seh_endprologue
; DISABLE-NEXT: testl %ecx, %ecx
-; DISABLE-NEXT: je .LBB0_4
+; DISABLE-NEXT: je .LBB0_5
; DISABLE-NEXT: # %bb.1: # %for.preheader
; DISABLE-NEXT: #APP
; DISABLE-NEXT: nop
@@ -74,11 +74,11 @@ define i32 @loopInfoSaveOutsideLoop(i32 %cond, i32 %N) #0 {
; DISABLE-NEXT: nop
; DISABLE-NEXT: #NO_APP
; DISABLE-NEXT: shll $3, %eax
-; DISABLE-NEXT: jmp .LBB0_5
-; DISABLE-NEXT: .LBB0_4: # %if.else
+; DISABLE-NEXT: popq %rbx
+; DISABLE-NEXT: retq
+; DISABLE-NEXT: .LBB0_5: # %if.else
; DISABLE-NEXT: movl %edx, %eax
; DISABLE-NEXT: addl %edx, %eax
-; DISABLE-NEXT: .LBB0_5: # %if.end
; DISABLE-NEXT: popq %rbx
; DISABLE-NEXT: retq
; DISABLE-NEXT: .seh_endproc
@@ -157,7 +157,7 @@ define i32 @loopInfoSaveOutsideLoop2(i32 %cond, i32 %N) #0 {
; DISABLE-NEXT: .seh_pushreg %rbx
; DISABLE-NEXT: .seh_endprologue
; DISABLE-NEXT: testl %ecx, %ecx
-; DISABLE-NEXT: je .LBB1_4
+; DISABLE-NEXT: je .LBB1_5
; DISABLE-NEXT: # %bb.1: # %for.preheader
; DISABLE-NEXT: #APP
; DISABLE-NEXT: nop
@@ -178,11 +178,11 @@ define i32 @loopInfoSaveOutsideLoop2(i32 %cond, i32 %N) #0 {
; DISABLE-NEXT: nop
; DISABLE-NEXT: #NO_APP
; DISABLE-NEXT: shll $3, %eax
-; DISABLE-NEXT: jmp .LBB1_5
-; DISABLE-NEXT: .LBB1_4: # %if.else
+; DISABLE-NEXT: popq %rbx
+; DISABLE-NEXT: retq
+; DISABLE-NEXT: .LBB1_5: # %if.else
; DISABLE-NEXT: addl %edx, %edx
; DISABLE-NEXT: movl %edx, %eax
-; DISABLE-NEXT: .LBB1_5: # %if.end
; DISABLE-NEXT: popq %rbx
; DISABLE-NEXT: retq
; DISABLE-NEXT: .seh_endproc
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efriedma-quic
approved these changes
Oct 18, 2024
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When adding new SEH pseudo instructions in #110024 I noticed that some of the tests were changing their output since these new instructions were counting towards thresholds for branching versus folding decisions.
These instructions do not result in real machine instructions being emitted, so they should be marked as meta instructions.
This is a re-do of #110889 as we hit an issue where some of the SEH pseudo instructions in the prolog were being duplicated, which resulted errors being raised as the CodeView generator was seeing prolog directives after an end-prolog directive: #110889 (comment). The fix for this is to mark the prolog related SEH pseudo instructions as being non-duplicatable.