Generate better location ranges for some register-described variables.
Don't terminate location ranges for register-described variables
at the end of machine basic block if this register is never modified
in the function body, except for the prologue and epilogue. Prologue
location is guessed by FrameSetup flags on MachineInstructions, while
epilogue location is deduced from debug locations of instructions
in the basic blocks ending with return instructions.
This patch is mostly targeted to fix non-trivial debug locations for
variables addressed via stack and frame pointers.
It is not really a generic fix. We can still produce poor debug info
for register-described variables if this register *is* modified somewhere
in the function, but in unrelated places. This might be the case for the debug
info in optimized binaries (e.g. for local variables in inlined functions).
LiveDebugVariables pass in CodeGen attempts to fix this problem by adjusting
DBG_VALUE instructions, but this pass is tied to greedy register allocator,
which is used in optimized builds only. Proper fix would likely involve
generalizing LiveDebugVariables to all register allocators. See more discussion
in http://reviews.llvm.org/D3933 review thread.
I'm proceeding with this patch to fix immediate severe problems and
important cases, e.g. fix completely broken debug info with AddressSanitizer
and fix PR19307 (missing debug info for by-value std::string arguments).
llvm-svn: 210492
diff --git a/llvm/test/DebugInfo/X86/debug-loc-offset.ll b/llvm/test/DebugInfo/X86/debug-loc-offset.ll
index 3f4d39d..244aa53 100644
--- a/llvm/test/DebugInfo/X86/debug-loc-offset.ll
+++ b/llvm/test/DebugInfo/X86/debug-loc-offset.ll
@@ -3,20 +3,23 @@
; From the code:
-; bar.cpp
+; debug-loc-offset1.cc
; int bar (int b) {
; return b+4;
; }
-; foo.cpp
+; debug-loc-offset2.cc
; struct A {
-; int a;
-; int b;
-; int c;
+; int var;
+; virtual char foo();
; };
-; int a (struct A var) {
-; return var.a;
+; void baz(struct A a) {
+; int z = 2;
+; if (a.var > 2)
+; z++;
+; if (a.foo() == 'a')
+; z++;
; }
; Compiled separately for i386-pc-linux-gnu and linked together.
@@ -38,78 +41,111 @@
; CHECK: DW_TAG_subprogram
; CHECK-NOT: DW_TAG
-; CHECK: DW_AT_MIPS_linkage_name [DW_FORM_strp]{{.*}}"_Z1a1A"
+; CHECK: DW_AT_MIPS_linkage_name [DW_FORM_strp]{{.*}}"_Z3baz1A"
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_formal_parameter
-; CHECK-NEXT: DW_AT_name [DW_FORM_strp]{{.*}}"var"
+; CHECK-NEXT: DW_AT_name [DW_FORM_strp]{{.*}}"a"
; CHECK: DW_AT_location [DW_FORM_sec_offset] (0x00000000)
+
+; CHECK: DW_TAG_variable
+; CHECK: DW_AT_location [DW_FORM_exprloc]
; CHECK-NOT: DW_AT_location
; CHECK: .debug_loc contents:
; CHECK: 0x00000000: Beginning address offset: 0x0000000000000000
-; CHECK: Ending address offset: 0x0000000000000009
+; CHECK: Ending address offset: 0x000000000000001a
-
-%struct.A = type { i32, i32, i32 }
+%struct.A = type { i32 (...)**, i32 }
; Function Attrs: nounwind
define i32 @_Z3bari(i32 %b) #0 {
entry:
%b.addr = alloca i32, align 4
store i32 %b, i32* %b.addr, align 4
- call void @llvm.dbg.declare(metadata !{i32* %b.addr}, metadata !25), !dbg !26
- %0 = load i32* %b.addr, align 4, !dbg !27
- %add = add nsw i32 %0, 4, !dbg !27
- ret i32 %add, !dbg !27
+ call void @llvm.dbg.declare(metadata !{i32* %b.addr}, metadata !21), !dbg !22
+ %0 = load i32* %b.addr, align 4, !dbg !23
+ %add = add nsw i32 %0, 4, !dbg !23
+ ret i32 %add, !dbg !23
}
; Function Attrs: nounwind readnone
declare void @llvm.dbg.declare(metadata, metadata) #1
-; Function Attrs: nounwind
-define i32 @_Z1a1A(%struct.A* byval align 4 %var) #0 {
+define void @_Z3baz1A(%struct.A* %a) #2 {
entry:
- call void @llvm.dbg.declare(metadata !{%struct.A* %var}, metadata !28), !dbg !29
- %a = getelementptr inbounds %struct.A* %var, i32 0, i32 0, !dbg !30
- %0 = load i32* %a, align 4, !dbg !30
- ret i32 %0, !dbg !30
+ %z = alloca i32, align 4
+ call void @llvm.dbg.declare(metadata !{%struct.A* %a}, metadata !24), !dbg !25
+ call void @llvm.dbg.declare(metadata !{i32* %z}, metadata !26), !dbg !27
+ store i32 2, i32* %z, align 4, !dbg !27
+ %var = getelementptr inbounds %struct.A* %a, i32 0, i32 1, !dbg !28
+ %0 = load i32* %var, align 4, !dbg !28
+ %cmp = icmp sgt i32 %0, 2, !dbg !28
+ br i1 %cmp, label %if.then, label %if.end, !dbg !28
+
+if.then: ; preds = %entry
+ %1 = load i32* %z, align 4, !dbg !30
+ %inc = add nsw i32 %1, 1, !dbg !30
+ store i32 %inc, i32* %z, align 4, !dbg !30
+ br label %if.end, !dbg !30
+
+if.end: ; preds = %if.then, %entry
+ %call = call signext i8 @_ZN1A3fooEv(%struct.A* %a), !dbg !31
+ %conv = sext i8 %call to i32, !dbg !31
+ %cmp1 = icmp eq i32 %conv, 97, !dbg !31
+ br i1 %cmp1, label %if.then2, label %if.end4, !dbg !31
+
+if.then2: ; preds = %if.end
+ %2 = load i32* %z, align 4, !dbg !33
+ %inc3 = add nsw i32 %2, 1, !dbg !33
+ store i32 %inc3, i32* %z, align 4, !dbg !33
+ br label %if.end4, !dbg !33
+
+if.end4: ; preds = %if.then2, %if.end
+ ret void, !dbg !34
}
+declare signext i8 @_ZN1A3fooEv(%struct.A*) #2
+
attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { nounwind readnone }
+attributes #2 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
!llvm.dbg.cu = !{!0, !9}
-!llvm.module.flags = !{!22, !23}
-!llvm.ident = !{!24, !24}
+!llvm.module.flags = !{!18, !19}
+!llvm.ident = !{!20, !20}
-!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 (trunk 204264) (llvm/trunk 204286)", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !"", i32 1}
-!1 = metadata !{metadata !"bar.cpp", metadata !"/usr/local/google/home/echristo/tmp"}
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 (210479)", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/llvm_cmake_gcc/debug-loc-offset1.cc] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"debug-loc-offset1.cc", metadata !"/llvm_cmake_gcc"}
!2 = metadata !{}
!3 = metadata !{metadata !4}
!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"bar", metadata !"bar", metadata !"_Z3bari", i32 1, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @_Z3bari, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [bar]
-!5 = metadata !{i32 786473, metadata !1} ; [ DW_TAG_file_type ] [/usr/local/google/home/echristo/tmp/bar.cpp]
+!5 = metadata !{i32 786473, metadata !1} ; [ DW_TAG_file_type ] [/llvm_cmake_gcc/debug-loc-offset1.cc]
!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
!7 = metadata !{metadata !8, metadata !8}
!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
-!9 = metadata !{i32 786449, metadata !10, i32 4, metadata !"clang version 3.5.0 (trunk 204264) (llvm/trunk 204286)", i1 false, metadata !"", i32 0, metadata !2, metadata !11, metadata !17, metadata !2, metadata !2, metadata !"", i32 1}
-!10 = metadata !{metadata !"foo.cpp", metadata !"/usr/local/google/home/echristo/tmp"}
+!9 = metadata !{i32 786449, metadata !10, i32 4, metadata !"clang version 3.5.0 (210479)", i1 false, metadata !"", i32 0, metadata !2, metadata !11, metadata !13, metadata !2, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/llvm_cmake_gcc/debug-loc-offset2.cc] [DW_LANG_C_plus_plus]
+!10 = metadata !{metadata !"debug-loc-offset2.cc", metadata !"/llvm_cmake_gcc"}
!11 = metadata !{metadata !12}
-!12 = metadata !{i32 786451, metadata !10, null, metadata !"A", i32 1, i64 96, i64 32, i32 0, i32 0, null, metadata !13, i32 0, null, null, metadata !"_ZTS1A"} ; [ DW_TAG_structure_type ] [A] [line 1, size 96, align 32, offset 0] [def] [from ]
-!13 = metadata !{metadata !14, metadata !15, metadata !16}
-!14 = metadata !{i32 786445, metadata !10, metadata !"_ZTS1A", metadata !"a", i32 2, i64 32, i64 32, i64 0, i32 0, metadata !8} ; [ DW_TAG_member ] [a] [line 2, size 32, align 32, offset 0] [from int]
-!15 = metadata !{i32 786445, metadata !10, metadata !"_ZTS1A", metadata !"b", i32 3, i64 32, i64 32, i64 32, i32 0, metadata !8} ; [ DW_TAG_member ] [b] [line 3, size 32, align 32, offset 32] [from int]
-!16 = metadata !{i32 786445, metadata !10, metadata !"_ZTS1A", metadata !"c", i32 4, i64 32, i64 32, i64 64, i32 0, metadata !8} ; [ DW_TAG_member ] [c] [line 4, size 32, align 32, offset 64] [from int]
-!17 = metadata !{metadata !18}
-!18 = metadata !{i32 786478, metadata !10, metadata !19, metadata !"a", metadata !"a", metadata !"_Z1a1A", i32 7, metadata !20, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (%struct.A*)* @_Z1a1A, null, null, metadata !2, i32 7} ; [ DW_TAG_subprogram ] [line 7] [def] [a]
-!19 = metadata !{i32 786473, metadata !10} ; [ DW_TAG_file_type ] [/usr/local/google/home/echristo/tmp/foo.cpp]
-!20 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !21, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
-!21 = metadata !{metadata !8, metadata !12}
-!22 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
-!23 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
-!24 = metadata !{metadata !"clang version 3.5.0 (trunk 204264) (llvm/trunk 204286)"}
-!25 = metadata !{i32 786689, metadata !4, metadata !"b", metadata !5, i32 16777217, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [b] [line 1]
-!26 = metadata !{i32 1, i32 0, metadata !4, null}
-!27 = metadata !{i32 2, i32 0, metadata !4, null}
-!28 = metadata !{i32 786689, metadata !18, metadata !"var", metadata !19, i32 16777223, metadata !"_ZTS1A", i32 0, i32 0}
-!29 = metadata !{i32 7, i32 0, metadata !18, null}
-!30 = metadata !{i32 8, i32 0, metadata !18, null} ; [ DW_TAG_imported_declaration ]
+!12 = metadata !{i32 786451, metadata !10, null, metadata !"A", i32 1, i64 0, i64 0, i32 0, i32 4, null, null, i32 0, null, null, metadata !"_ZTS1A"} ; [ DW_TAG_structure_type ] [A] [line 1, size 0, align 0, offset 0] [decl] [from ]
+!13 = metadata !{metadata !14}
+!14 = metadata !{i32 786478, metadata !10, metadata !15, metadata !"baz", metadata !"baz", metadata !"_Z3baz1A", i32 6, metadata !16, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, void (%struct.A*)* @_Z3baz1A, null, null, metadata !2, i32 6} ; [ DW_TAG_subprogram ] [line 6] [def] [baz]
+!15 = metadata !{i32 786473, metadata !10} ; [ DW_TAG_file_type ] [/llvm_cmake_gcc/debug-loc-offset2.cc]
+!16 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !17, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!17 = metadata !{null, metadata !12}
+!18 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!19 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}
+!20 = metadata !{metadata !"clang version 3.5.0 (210479)"}
+!21 = metadata !{i32 786689, metadata !4, metadata !"b", metadata !5, i32 16777217, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [b] [line 1]
+!22 = metadata !{i32 1, i32 0, metadata !4, null}
+!23 = metadata !{i32 2, i32 0, metadata !4, null}
+!24 = metadata !{i32 786689, metadata !14, metadata !"a", metadata !15, i32 16777222, metadata !"_ZTS1A", i32 8192, i32 0} ; [ DW_TAG_arg_variable ] [a] [line 6]
+!25 = metadata !{i32 6, i32 0, metadata !14, null}
+!26 = metadata !{i32 786688, metadata !14, metadata !"z", metadata !15, i32 7, metadata !8, i32 0, i32 0} ; [ DW_TAG_auto_variable ] [z] [line 7]
+!27 = metadata !{i32 7, i32 0, metadata !14, null}
+!28 = metadata !{i32 8, i32 0, metadata !29, null} ; [ DW_TAG_imported_declaration ]
+!29 = metadata !{i32 786443, metadata !10, metadata !14, i32 8, i32 0, i32 0, i32 0} ; [ DW_TAG_lexical_block ] [/llvm_cmake_gcc/debug-loc-offset2.cc]
+!30 = metadata !{i32 9, i32 0, metadata !29, null}
+!31 = metadata !{i32 10, i32 0, metadata !32, null}
+!32 = metadata !{i32 786443, metadata !10, metadata !14, i32 10, i32 0, i32 0, i32 1} ; [ DW_TAG_lexical_block ] [/llvm_cmake_gcc/debug-loc-offset2.cc]
+!33 = metadata !{i32 11, i32 0, metadata !32, null}
+!34 = metadata !{i32 12, i32 0, metadata !14, null}