e48597a50e
A cast from A to B is eliminable if its result is casted to C, and if the pair of casts could just be expressed as a single cast. E.g here, %c1 is eliminable: %c1 = zext i16 %A to i32 %c2 = sext i32 %c1 to i64 InstCombine optimizes away eliminable casts. This patch teaches it to insert a dbg.value intrinsic pointing to the final result, so that local variables pointing to the eliminable result are preserved. Differential Revision: https://reviews.llvm.org/D42566 llvm-svn: 323570
19 lines
908 B
LLVM
19 lines
908 B
LLVM
; RUN: opt < %s -debugify -instcombine -S | FileCheck %s
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define i64 @test_sext_zext(i16 %A) {
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; CHECK-LABEL: @test_sext_zext(
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; CHECK-NEXT: [[C2:%.*]] = zext i16 %A to i64
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; CHECK-NEXT: call void @llvm.dbg.value(metadata i64 [[C2]], metadata !8, metadata !DIExpression()), !dbg !13
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; CHECK-NEXT: call void @llvm.dbg.value(metadata i64 [[C2]], metadata !10, metadata !DIExpression()), !dbg !12
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%c1 = zext i16 %A to i32
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%c2 = sext i32 %c1 to i64
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ret i64 %c2
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}
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; CHECK: !8 = !DILocalVariable(name: "1", scope: !5, file: !1, line: 1, type: !9)
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; CHECK: !9 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
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; CHECK: !10 = !DILocalVariable(name: "2", scope: !5, file: !1, line: 2, type: !11)
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; CHECK: !11 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
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; CHECK: !12 = !DILocation(line: 2, column: 1, scope: !5)
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; CHECK: !13 = !DILocation(line: 1, column: 1, scope: !5)
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