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llvm-mirror/test/DebugInfo/X86/live-debug-values-expr-conflict.ll
Jeremy Morse 360bcb66b4 [DebugInfo] LiveDebugValues: locations with different exprs should not be merged
When comparing variable locations, LiveDebugValues currently considers only
the machine location, ignoring any DIExpression applied to it. This is a
problem because that DIExpression can do pretty much anything to the machine
location, for example dereferencing it.

This patch adds DIExpressions to that comparison; now variables based on the
same register/memory-location but with different expressions will compare
differently, and be dropped if we attempt to merge them between blocks. This
reduces variable coverage-range a little, but only because we were producing
broken locations.

Differential Revision: https://reviews.llvm.org/D66942

llvm-svn: 370877
2019-09-04 11:09:05 +00:00

76 lines
2.7 KiB
LLVM

; RUN: llc %s -mtriple=x86_64-unknown-unknown -o - -stop-after=livedebugvalues | FileCheck %s
;
; In the C below, 'baz' is re-assigned with a value that gets salvaged, making
; it's dbg.value base itself on 'bar', but with a complex expression.
; LiveDebugValues should recognize that these are different locations, and not
; propagate a location for 'baz' into the return block.
;
; void escape1(int bees);
; void escape2(int bees);
;
; int foo(int bar) {
; int baz = bar;
; if (baz == 12) {
; escape1(bar);
; } else {
; baz += 1;
; escape2(bar);
; }
;
; return bar;
; }
;
; We should get a plain DBG_VALUE in the entry block, a plain one then complex
; one in the block two, and none in block three.
; CHECK: ![[BAZVAR:[0-9]+]] = !DILocalVariable(name: "baz",
; CHECK-LABEL: bb.0.entry:
; CHECK: DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
; CHECK-SAME: !DIExpression()
; CHECK-LABEL: bb.1.if.then:
; CHECK-LABEL: bb.2.if.else:
; CHECK: DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
; CHECK-SAME: !DIExpression()
; CHECK: DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
; CHECK-SAME: !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value)
; CHECK-LABEL: bb.3.if.end:
; CHECK-NOT: DBG_VALUE
declare void @escape1(i32)
declare void @escape2(i32)
declare void @llvm.dbg.value(metadata, metadata, metadata)
define i32 @foo(i32 returned %bar) !dbg !7 {
entry:
call void @llvm.dbg.value(metadata i32 %bar, metadata !13, metadata !DIExpression()), !dbg !14
%cmp = icmp eq i32 %bar, 12, !dbg !14
br i1 %cmp, label %if.then, label %if.else, !dbg !14
if.then:
tail call void @escape1(i32 12) #3, !dbg !14
br label %if.end, !dbg !14
if.else:
call void @llvm.dbg.value(metadata i32 %bar, metadata !13, metadata !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value)), !dbg !14
tail call void @escape2(i32 %bar) #3, !dbg !14
br label %if.end
if.end:
ret i32 %bar, !dbg !14
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
!1 = !DIFile(filename: "exprconflict.c", directory: "/home/jmorse")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 5, type: !8, scopeLine: 5, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
!8 = !DISubroutineType(types: !9)
!9 = !{!10, !10}
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!11 = !{!13}
!13 = !DILocalVariable(name: "baz", scope: !7, file: !1, line: 6, type: !10)
!14 = !DILocation(line: 1, scope: !7)