forked from OSchip/llvm-project
[DebugInfo] Emit DW_OP_implicit_value for Floating point constants
Summary:
llvm is missing support for DW_OP_implicit_value operation.
DW_OP_implicit_value op is indispensable for cases such as
optimized out long double variables.
For intro refer: DWARFv5 Spec Pg: 40 2.6.1.1.4 Implicit Location Descriptions
Consider the following example:
```
int main() {
long double ld = 3.14;
printf("dummy\n");
ld *= ld;
return 0;
}
```
when compiled with tunk `clang` as
`clang test.c -g -O1` produces following location description
of variable `ld`:
```
DW_AT_location (0x00000000:
[0x0000000000201691, 0x000000000020169b): DW_OP_constu 0xc8f5c28f5c28f800, DW_OP_stack_value, DW_OP_piece 0x8, DW_OP_constu 0x4000, DW_OP_stack_value, DW_OP_bit_piece 0x10 0x40, DW_OP_stack_value)
DW_AT_name ("ld")
```
Here one may notice that this representation is incorrect(DWARF4
stack could only hold integers(and only up to the size of address)).
Here the variable size itself is `128` bit.
GDB and LLDB confirms this:
```
(gdb) p ld
$1 = <invalid float value>
(lldb) frame variable ld
(long double) ld = <extracting data from value failed>
```
GCC represents/uses DW_OP_implicit_value in these sort of situations.
Based on the discussion with Jakub Jelinek regarding GCC's motivation
for using this, I concluded that DW_OP_implicit_value is most appropriate
in this case.
Link: https://gcc.gnu.org/pipermail/gcc/2020-July/233057.html
GDB seems happy after this patch:(LLDB doesn't have support
for DW_OP_implicit_value)
```
(gdb) p ld
p ld
$1 = 3.14000000000000012434
```
Reviewed By: aprantl
Differential Revision: https://reviews.llvm.org/D83560
This commit is contained in:
Sourabh Singh Tomar
parent
99ad956fda
commit
6b55a95898
|
|
@ -2512,8 +2512,20 @@ void DwarfDebug::emitDebugLocValue(const AsmPrinter &AP, const DIBasicType *BT,
|
|||
// encoding is supported.
|
||||
DwarfExpr.addWasmLocation(Loc.Index, static_cast<uint64_t>(Loc.Offset));
|
||||
} else if (Value.isConstantFP()) {
|
||||
APInt RawBytes = Value.getConstantFP()->getValueAPF().bitcastToAPInt();
|
||||
DwarfExpr.addUnsignedConstant(RawBytes);
|
||||
if (AP.getDwarfVersion() >= 4 && AP.getDwarfDebug()->tuneForGDB())
|
||||
DwarfExpr.addConstantFP(Value.getConstantFP()->getValueAPF());
|
||||
else if (Value.getConstantFP()
|
||||
->getValueAPF()
|
||||
.bitcastToAPInt()
|
||||
.getBitWidth() <= 64 /*bits*/)
|
||||
DwarfExpr.addUnsignedConstant(
|
||||
Value.getConstantFP()->getValueAPF().bitcastToAPInt());
|
||||
else
|
||||
LLVM_DEBUG(
|
||||
dbgs()
|
||||
<< "Skipped DwarfExpression creation for ConstantFP of size"
|
||||
<< Value.getConstantFP()->getValueAPF().bitcastToAPInt().getBitWidth()
|
||||
<< " bits\n");
|
||||
}
|
||||
DwarfExpr.addExpression(std::move(ExprCursor));
|
||||
}
|
||||
|
|
|
|||
|
|
@ -25,6 +25,8 @@
|
|||
|
||||
using namespace llvm;
|
||||
|
||||
#define DEBUG_TYPE "dwarfdebug"
|
||||
|
||||
void DwarfExpression::emitConstu(uint64_t Value) {
|
||||
if (Value < 32)
|
||||
emitOp(dwarf::DW_OP_lit0 + Value);
|
||||
|
|
@ -219,6 +221,36 @@ void DwarfExpression::addUnsignedConstant(const APInt &Value) {
|
|||
}
|
||||
}
|
||||
|
||||
void DwarfExpression::addConstantFP(const APFloat &Value) {
|
||||
assert(isImplicitLocation() || isUnknownLocation());
|
||||
APInt RawBytes = Value.bitcastToAPInt();
|
||||
int NumBytes = RawBytes.getBitWidth() / 8;
|
||||
const char *Data = (const char *)RawBytes.getRawData();
|
||||
emitOp(dwarf::DW_OP_implicit_value);
|
||||
if (NumBytes == 4 /*float*/ || NumBytes == 8 /*double*/) {
|
||||
emitUnsigned(NumBytes /*Size of the block in bytes*/);
|
||||
for (int i = 0; i < NumBytes; ++i)
|
||||
emitData1(Data[i]);
|
||||
return;
|
||||
}
|
||||
if (NumBytes == 10 /*long double*/) {
|
||||
// long double IEEE representation uses 80 bits(10 bytes).
|
||||
// 6 bytes are padded to make it 128 bits(16 bytes) due to
|
||||
// addressing restrictions.
|
||||
emitUnsigned(16 /*Size of the block in bytes*/);
|
||||
// Emit the block of bytes.
|
||||
for (int i = 0; i < NumBytes; ++i)
|
||||
emitData1(Data[i]);
|
||||
// Emit the rest as padding bytes.
|
||||
for (int i = 0; i < 16 - NumBytes; ++i)
|
||||
emitData1(0);
|
||||
return;
|
||||
}
|
||||
LLVM_DEBUG(
|
||||
dbgs() << "Skipped DW_OP_implicit_value creation for ConstantFP of size"
|
||||
<< RawBytes.getBitWidth() << " bits\n");
|
||||
}
|
||||
|
||||
bool DwarfExpression::addMachineRegExpression(const TargetRegisterInfo &TRI,
|
||||
DIExpressionCursor &ExprCursor,
|
||||
unsigned MachineReg,
|
||||
|
|
|
|||
|
|
@ -299,6 +299,9 @@ public:
|
|||
/// Emit an unsigned constant.
|
||||
void addUnsignedConstant(const APInt &Value);
|
||||
|
||||
/// Emit floating point constant.
|
||||
void addConstantFP(const APFloat &Value);
|
||||
|
||||
/// Lock this down to become a memory location description.
|
||||
void setMemoryLocationKind() {
|
||||
assert(isUnknownLocation());
|
||||
|
|
|
|||
|
|
@ -20,12 +20,10 @@
|
|||
;
|
||||
; CHECK: .debug_info contents:
|
||||
; CHECK: DW_TAG_variable
|
||||
; CHECK-NEXT: DW_AT_location {{.*}} (
|
||||
; CHECK-NEXT: [0x[[START:.*]], 0x[[END:.*]]): DW_OP_constu 0xc8f5c28f5c28f800, DW_OP_piece 0x8, DW_OP_constu 0x4000, DW_OP_bit_piece 0x10 0x40)
|
||||
; CHECK-NEXT: DW_AT_name {{.*}}"ld"
|
||||
; CHECK: DW_TAG_variable
|
||||
; CHECK-NEXT: DW_AT_location {{.*}} (
|
||||
; CHECK-NEXT: [0x[[START]], 0x[[END]]): DW_OP_constu 0x4048f5c3)
|
||||
; CHECK-NEXT: [0x{{.*}}, 0x{{.*}}): DW_OP_constu 0x4048f5c3)
|
||||
; CHECK-NEXT: DW_AT_name {{.*}}"f"
|
||||
|
||||
source_filename = "test.c"
|
||||
|
|
|
|||
|
|
@ -0,0 +1,66 @@
|
|||
;; This test checks for emission of DW_OP_implicit_value operation
|
||||
;; for double type.
|
||||
|
||||
; RUN: llc -debugger-tune=gdb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s
|
||||
|
||||
; CHECK: .debug_info contents:
|
||||
; CHECK: DW_TAG_variable
|
||||
; CHECK-NEXT: DW_AT_location ({{.*}}
|
||||
; CHECK-NEXT: [{{.*}}): DW_OP_implicit_value 0x8 0x1f 0x85 0xeb 0x51 0xb8 0x1e 0x09 0x40)
|
||||
; CHECK-NEXT: DW_AT_name ("d")
|
||||
|
||||
;; Generated from: clang -ggdb -O1
|
||||
;;int main() {
|
||||
;; double d = 3.14;
|
||||
;; printf("dummy\n");
|
||||
;; d *= d;
|
||||
;; return 0;
|
||||
;;}
|
||||
|
||||
; ModuleID = 'implicit_value-double.c'
|
||||
source_filename = "implicit_value-double.c"
|
||||
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
|
||||
target triple = "x86_64-unknown-linux-gnu"
|
||||
|
||||
@str = private unnamed_addr constant [6 x i8] c"dummy\00", align 1
|
||||
|
||||
; Function Attrs: nofree nounwind uwtable
|
||||
define dso_local i32 @main() local_unnamed_addr #0 !dbg !7 {
|
||||
entry:
|
||||
call void @llvm.dbg.value(metadata double 3.140000e+00, metadata !12, metadata !DIExpression()), !dbg !14
|
||||
%puts = call i32 @puts(i8* nonnull dereferenceable(1) getelementptr inbounds ([6 x i8], [6 x i8]* @str, i64 0, i64 0)), !dbg !15
|
||||
call void @llvm.dbg.value(metadata double undef, metadata !12, metadata !DIExpression()), !dbg !14
|
||||
ret i32 0, !dbg !16
|
||||
}
|
||||
|
||||
; Function Attrs: nounwind readnone speculatable willreturn
|
||||
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
|
||||
|
||||
; Function Attrs: nofree nounwind
|
||||
declare i32 @puts(i8* nocapture readonly) local_unnamed_addr #2
|
||||
|
||||
attributes #0 = { nofree nounwind uwtable }
|
||||
attributes #1 = { nounwind readnone speculatable willreturn }
|
||||
attributes #2 = { nofree nounwind }
|
||||
|
||||
!llvm.dbg.cu = !{!0}
|
||||
!llvm.module.flags = !{!3, !4, !5}
|
||||
!llvm.ident = !{!6}
|
||||
|
||||
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 11.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
|
||||
!1 = !DIFile(filename: "implicit_value-double.c", directory: "/home/")
|
||||
!2 = !{}
|
||||
!3 = !{i32 7, !"Dwarf Version", i32 4}
|
||||
!4 = !{i32 2, !"Debug Info Version", i32 3}
|
||||
!5 = !{i32 1, !"wchar_size", i32 4}
|
||||
!6 = !{!"clang version 11.0.0"}
|
||||
!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
|
||||
!8 = !DISubroutineType(types: !9)
|
||||
!9 = !{!10}
|
||||
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
|
||||
!11 = !{!12}
|
||||
!12 = !DILocalVariable(name: "d", scope: !7, file: !1, line: 2, type: !13)
|
||||
!13 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
|
||||
!14 = !DILocation(line: 0, scope: !7)
|
||||
!15 = !DILocation(line: 3, column: 2, scope: !7)
|
||||
!16 = !DILocation(line: 5, column: 2, scope: !7)
|
||||
|
|
@ -0,0 +1,65 @@
|
|||
;; This test checks for emission of DW_OP_implicit_value operation
|
||||
;; for float type.
|
||||
|
||||
; RUN: llc -debugger-tune=gdb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s
|
||||
|
||||
; CHECK: .debug_info contents:
|
||||
; CHECK: DW_TAG_variable
|
||||
; CHECK-NEXT: DW_AT_location ({{.*}}
|
||||
; CHECK-NEXT: [{{.*}}): DW_OP_implicit_value 0x4 0xc3 0xf5 0x48 0x40)
|
||||
; CHECK-NEXT: DW_AT_name ("f")
|
||||
|
||||
;; Generated from: clang -ggdb -O1
|
||||
;;int main() {
|
||||
;; float f = 3.14f;
|
||||
;; printf("dummy\n");
|
||||
;; f *= f;
|
||||
;; return 0;
|
||||
;;}
|
||||
; ModuleID = 'implicit_value-float.c'
|
||||
source_filename = "implicit_value-float.c"
|
||||
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
|
||||
target triple = "x86_64-unknown-linux-gnu"
|
||||
|
||||
@str = private unnamed_addr constant [6 x i8] c"dummy\00", align 1
|
||||
|
||||
; Function Attrs: nofree nounwind uwtable
|
||||
define dso_local i32 @main() local_unnamed_addr #0 !dbg !7 {
|
||||
entry:
|
||||
call void @llvm.dbg.value(metadata float 0x40091EB860000000, metadata !12, metadata !DIExpression()), !dbg !14
|
||||
%puts = call i32 @puts(i8* nonnull dereferenceable(1) getelementptr inbounds ([6 x i8], [6 x i8]* @str, i64 0, i64 0)), !dbg !15
|
||||
call void @llvm.dbg.value(metadata float undef, metadata !12, metadata !DIExpression()), !dbg !14
|
||||
ret i32 0, !dbg !16
|
||||
}
|
||||
|
||||
; Function Attrs: nounwind readnone speculatable willreturn
|
||||
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
|
||||
|
||||
; Function Attrs: nofree nounwind
|
||||
declare i32 @puts(i8* nocapture readonly) local_unnamed_addr #2
|
||||
|
||||
attributes #0 = { nofree nounwind uwtable }
|
||||
attributes #1 = { nounwind readnone speculatable willreturn }
|
||||
attributes #2 = { nofree nounwind }
|
||||
|
||||
!llvm.dbg.cu = !{!0}
|
||||
!llvm.module.flags = !{!3, !4, !5}
|
||||
!llvm.ident = !{!6}
|
||||
|
||||
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 11.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
|
||||
!1 = !DIFile(filename: "implicit_value-float.c", directory: "/home/")
|
||||
!2 = !{}
|
||||
!3 = !{i32 7, !"Dwarf Version", i32 4}
|
||||
!4 = !{i32 2, !"Debug Info Version", i32 3}
|
||||
!5 = !{i32 1, !"wchar_size", i32 4}
|
||||
!6 = !{!"clang version 11.0.0"}
|
||||
!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
|
||||
!8 = !DISubroutineType(types: !9)
|
||||
!9 = !{!10}
|
||||
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
|
||||
!11 = !{!12}
|
||||
!12 = !DILocalVariable(name: "f", scope: !7, file: !1, line: 2, type: !13)
|
||||
!13 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
|
||||
!14 = !DILocation(line: 0, scope: !7)
|
||||
!15 = !DILocation(line: 3, column: 2, scope: !7)
|
||||
!16 = !DILocation(line: 5, column: 2, scope: !7)
|
||||
|
|
@ -0,0 +1,71 @@
|
|||
;; This test checks for emission of DW_OP_implicit_value operation
|
||||
;; for long double type.
|
||||
|
||||
; RUN: llc -debugger-tune=gdb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s
|
||||
|
||||
; CHECK: .debug_info contents:
|
||||
; CHECK: DW_TAG_variable
|
||||
; CHECK-NEXT: DW_AT_location ({{.*}}
|
||||
; CHECK-NEXT: [{{.*}}): DW_OP_implicit_value 0x10 0x00 0xf8 0x28 0x5c 0x8f 0xc2 0xf5 0xc8 0x00 0x40 0x00 0x00 0x00 0x00 0x00 0x00)
|
||||
; CHECK-NEXT: DW_AT_name ("ld")
|
||||
|
||||
;; Generated from: clang -ggdb -O1
|
||||
;;int main() {
|
||||
;; long double ld = 3.14;
|
||||
;; printf("dummy\n");
|
||||
;; ld *= ld;
|
||||
;; return 0;
|
||||
;;}
|
||||
|
||||
; ModuleID = 'implicit_value-ld.c'
|
||||
source_filename = "implicit_value-ld.c"
|
||||
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
|
||||
target triple = "x86_64-unknown-linux-gnu"
|
||||
|
||||
@str = private unnamed_addr constant [6 x i8] c"dummy\00", align 1
|
||||
|
||||
; Function Attrs: nofree nounwind uwtable
|
||||
define dso_local i32 @main() local_unnamed_addr #0 !dbg !7 {
|
||||
entry:
|
||||
call void @llvm.dbg.declare(metadata [6 x i8]* undef, metadata !12, metadata !DIExpression(DW_OP_LLVM_fragment, 80, 48)), !dbg !14
|
||||
call void @llvm.dbg.value(metadata x86_fp80 0xK4000C8F5C28F5C28F800, metadata !12, metadata !DIExpression()), !dbg !15
|
||||
%puts = call i32 @puts(i8* nonnull dereferenceable(1) getelementptr inbounds ([6 x i8], [6 x i8]* @str, i64 0, i64 0)), !dbg !16
|
||||
call void @llvm.dbg.value(metadata x86_fp80 undef, metadata !12, metadata !DIExpression()), !dbg !15
|
||||
ret i32 0, !dbg !17
|
||||
}
|
||||
|
||||
; Function Attrs: nounwind readnone speculatable willreturn
|
||||
declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
|
||||
|
||||
; Function Attrs: nounwind readnone speculatable willreturn
|
||||
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
|
||||
|
||||
; Function Attrs: nofree nounwind
|
||||
declare i32 @puts(i8* nocapture readonly) local_unnamed_addr #2
|
||||
|
||||
attributes #0 = { nofree nounwind uwtable }
|
||||
attributes #1 = { nounwind readnone speculatable willreturn }
|
||||
attributes #2 = { nofree nounwind }
|
||||
|
||||
!llvm.dbg.cu = !{!0}
|
||||
!llvm.module.flags = !{!3, !4, !5}
|
||||
!llvm.ident = !{!6}
|
||||
|
||||
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 11.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
|
||||
!1 = !DIFile(filename: "implicit_value-ld.c", directory: "/home/")
|
||||
!2 = !{}
|
||||
!3 = !{i32 7, !"Dwarf Version", i32 4}
|
||||
!4 = !{i32 2, !"Debug Info Version", i32 3}
|
||||
!5 = !{i32 1, !"wchar_size", i32 4}
|
||||
!6 = !{!"clang version 11.0.0"}
|
||||
!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
|
||||
!8 = !DISubroutineType(types: !9)
|
||||
!9 = !{!10}
|
||||
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
|
||||
!11 = !{!12}
|
||||
!12 = !DILocalVariable(name: "ld", scope: !7, file: !1, line: 2, type: !13)
|
||||
!13 = !DIBasicType(name: "long double", size: 128, encoding: DW_ATE_float)
|
||||
!14 = !DILocation(line: 2, column: 14, scope: !7)
|
||||
!15 = !DILocation(line: 0, scope: !7)
|
||||
!16 = !DILocation(line: 3, column: 2, scope: !7)
|
||||
!17 = !DILocation(line: 5, column: 2, scope: !7)
|
||||
Loading…
Reference in New Issue