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57907269da
so we can stop using DW_OP_bit_piece with the wrong semantics. The entire back story can be found here: http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20161114/405934.html The gist is that in LLVM we've been misinterpreting DW_OP_bit_piece's offset field to mean the offset into the source variable rather than the offset into the location at the top the DWARF expression stack. In order to be able to fix this in a subsequent patch, this patch introduces a dedicated DW_OP_LLVM_fragment operation with the semantics that we used to apply to DW_OP_bit_piece, which is what we actually need while inside of LLVM. This patch is complete with a bitcode upgrade for expressions using the old format. It does not yet fix the DWARF backend to use DW_OP_bit_piece correctly. Implementation note: We discussed several options for implementing this, including reserving a dedicated field in DIExpression for the fragment size and offset, but using an custom operator at the end of the expression works just fine and is more efficient because we then only pay for it when we need it. Differential Revision: https://reviews.llvm.org/D27361 rdar://problem/29335809 llvm-svn: 288683
85 lines
4.5 KiB
LLVM
85 lines
4.5 KiB
LLVM
; RUN: llc < %s | FileCheck %s
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; Compile the following with -O1:
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; struct IntPair { int x, y; };
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; int g(void);
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; int bitpiece_spill() {
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; struct IntPair o = {g(), 0};
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; // Force o.x to spill
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; asm volatile("" : : : "rax", "rbx", "rcx", "rdx", "rsi", "rdi", "rbp",
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; "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15");
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; return o.x;
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; }
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; CHECK-LABEL: bitpiece_spill: # @bitpiece_spill
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; CHECK: callq g
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; CHECK: movl %eax, [[offs:[0-9]+]](%rsp) # 4-byte Spill
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; CHECK: #DEBUG_VALUE: bitpiece_spill:o [fragment offset=32 size=32] <- 0
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; CHECK: #DEBUG_VALUE: bitpiece_spill:o [fragment offset=0 size=32] <- [%RSP+[[offs]]]
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; CHECK: #APP
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; CHECK: #NO_APP
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; CHECK: movl [[offs]](%rsp), %eax # 4-byte Reload
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; CHECK: retq
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; ModuleID = 't.c'
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source_filename = "t.c"
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target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-pc-windows-msvc19.0.24210"
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%struct.IntPair = type { i32, i32 }
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; Function Attrs: nounwind uwtable
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define i32 @bitpiece_spill() local_unnamed_addr #0 !dbg !7 {
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entry:
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tail call void @llvm.dbg.declare(metadata %struct.IntPair* undef, metadata !12, metadata !17), !dbg !18
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%call = tail call i32 @g() #3, !dbg !19
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tail call void @llvm.dbg.value(metadata i32 %call, i64 0, metadata !12, metadata !20), !dbg !18
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tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !12, metadata !21), !dbg !18
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tail call void asm sideeffect "", "~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"() #3, !dbg !22, !srcloc !23
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ret i32 %call, !dbg !24
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}
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; Function Attrs: nounwind readnone
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declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
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declare i32 @g() local_unnamed_addr #2
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; Function Attrs: nounwind readnone
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declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
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attributes #0 = { nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "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"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #1 = { nounwind readnone }
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attributes #2 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #3 = { nounwind }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
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!1 = !DIFile(filename: "t.c", directory: "C:\5Csrc\5Cllvm\5Cbuild")
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!2 = !{}
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!3 = !{i32 2, !"Dwarf Version", i32 4}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!5 = !{i32 1, !"PIC Level", i32 2}
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!6 = !{!"clang version 4.0.0 "}
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!7 = distinct !DISubprogram(name: "bitpiece_spill", scope: !1, file: !1, line: 3, type: !8, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: true, unit: !0, variables: !11)
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!8 = !DISubroutineType(types: !9)
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!9 = !{!10}
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!10 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
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!11 = !{!12}
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!12 = !DILocalVariable(name: "o", scope: !7, file: !1, line: 4, type: !13)
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!13 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "IntPair", file: !1, line: 1, size: 64, align: 32, elements: !14)
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!14 = !{!15, !16}
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!15 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !13, file: !1, line: 1, baseType: !10, size: 32, align: 32)
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!16 = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: !13, file: !1, line: 1, baseType: !10, size: 32, align: 32, offset: 32)
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!17 = !DIExpression()
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!18 = !DILocation(line: 4, column: 18, scope: !7)
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!19 = !DILocation(line: 4, column: 23, scope: !7)
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!20 = !DIExpression(DW_OP_LLVM_fragment, 0, 32)
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!21 = !DIExpression(DW_OP_LLVM_fragment, 32, 32)
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!22 = !DILocation(line: 6, column: 3, scope: !7)
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!23 = !{i32 138}
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!24 = !DILocation(line: 8, column: 3, scope: !7)
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