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[DebugInfo] Handle endianness when moving debug info for split integer values (reapplied) 

Summary:
Take the target's endianness into account when splitting the
debug information in DAGTypeLegalizer::SetExpandedInteger.

This patch fixes so that, for big-endian targets, the fragment
expression corresponding to the high part of a split integer
value is placed at offset 0, in order to correctly represent
the memory address order.

I have attached a PPC32 reproducer where the resulting DWARF
pieces for a 64-bit integer were incorrectly reversed.

Original patch was reverted due to using -stop-after=isel in
the test case (but that is only working when AMDGPU target
is included in the llc build). The test case has now been
updated to use -stop-before=expand-isel-pseudos instead.

Patch by: dstenb

Reviewers: JDevlieghere, aprantl, dblaikie

Reviewed By: JDevlieghere, aprantl, dblaikie

Subscribers: nemanjai

Differential Revision: https://reviews.llvm.org/D38172

llvm-svn: 314781
This commit is contained in:
Bjorn Pettersson 2017-10-03 11:03:02 +00:00
parent a511ed7501
commit 90cc1b53d0
2 changed files with 73 additions and 2 deletions
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9
llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
View File

@ -864,8 +864,13 @@ void DAGTypeLegalizer::SetExpandedInteger(SDValue Op, SDValue Lo,
AnalyzeNewValue(Hi);
// Transfer debug values.
transferDbgValues(DAG, Op, Lo, 0);
transferDbgValues(DAG, Op, Hi, Lo.getValueSizeInBits());
if (DAG.getDataLayout().isBigEndian()) {
transferDbgValues(DAG, Op, Hi, 0);
transferDbgValues(DAG, Op, Lo, Hi.getValueSizeInBits());
} else {
transferDbgValues(DAG, Op, Lo, 0);
transferDbgValues(DAG, Op, Hi, Lo.getValueSizeInBits());
}
// Remember that this is the result of the node.
std::pair<SDValue, SDValue> &Entry = ExpandedIntegers[Op];

66
llvm/test/CodeGen/PowerPC/debuginfo-split-int.ll Normal file
View File

@ -0,0 +1,66 @@
; RUN: llc < %s -stop-before=expand-isel-pseudos -o - | FileCheck %s
source_filename = "foo.c"
target datalayout = "E-m:e-p:32:32-i64:64-n32"
target triple = "ppc32"
; Verify that, when handling split-up integers, the
; transferring of debug info takes the endianness
; into consideration.
;
; The fragment expression at offset 0 should correspond
; to the high part of the value on big-endian targets.
; This basis of this ll file was created by running:
; clang --target=powerpc -O1 -S -g -emit-llvm foo.c
;
; with foo.c being the program:
; unsigned long long foo(void);
; void bar() {
; volatile unsigned long long result = foo();
; }
;
; This file is a slight tweak of that output, with irrelevant
; lifetime intrinsics, metadata, and debug info being removed.
; CHECK: [[DL:![0-9]+]] = !DILocalVariable(name: "result"
;
; High 32 bits in R3, low 32 bits in R4
; CHECK: %0 = COPY %r3
; CHECK: DBG_VALUE debug-use %0, debug-use _, [[DL]], !DIExpression(DW_OP_LLVM_fragment, 0, 32)
; CHECK: %1 = COPY %r4
; CHECK: DBG_VALUE debug-use %1, debug-use _, [[DL]], !DIExpression(DW_OP_LLVM_fragment, 32, 32)
define void @bar() local_unnamed_addr #0 !dbg !6 {
%1 = alloca i64, align 8
%2 = tail call i64 @foo()
tail call void @llvm.dbg.value(metadata i64 %2, metadata !10, metadata !DIExpression()), !dbg !13
store volatile i64 %2, i64* %1, align 8
ret void
}
declare i64 @foo() local_unnamed_addr
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
attributes #0 = { nounwind }
attributes #1 = { nounwind readnone speculatable }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
!llvm.ident = !{!5}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "foo.c", directory: "/")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{!"clang version 6.0.0"}
!6 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 2, type: !7, isLocal: false, isDefinition: true, scopeLine: 2, isOptimized: true, unit: !0, variables: !9)
!7 = !DISubroutineType(types: !8)
!8 = !{null}
!9 = !{!10}
!10 = !DILocalVariable(name: "result", scope: !6, file: !1, line: 3, type: !11)
!11 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !12)
!12 = !DIBasicType(name: "long long unsigned int", size: 64, encoding: DW_ATE_unsigned)
!13 = !DILocation(line: 3, column: 31, scope: !6)