[llvm] r297965 - PR32288: More efficient encoding for DWARF expr subregister access.
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 16 10:14:56 PDT 2017
Author: adrian
Date: Thu Mar 16 12:14:56 2017
New Revision: 297965
URL: http://llvm.org/viewvc/llvm-project?rev=297965&view=rev
Log:
PR32288: More efficient encoding for DWARF expr subregister access.
Citing http://bugs.llvm.org/show_bug.cgi?id=32288
The DWARF generated by LLVM includes this location:
0x55 0x93 0x04 DW_OP_reg5 DW_OP_piece(4) When GCC's DWARF is simply
0x55 (DW_OP_reg5) without the DW_OP_piece. I believe it's reasonable
to assume the DWARF consumer knows which part of a register
logically holds the value (low bytes, high bytes, how many bytes,
etc) for a primitive value like an integer.
This patch gets rid of the redundant DW_OP_piece when a subregister is
at offset 0. It also adds previously missing subregister masking when
a subregister is followed by another operation.
(This reapplies r297960 with two additional testcase updates).
rdar://problem/31069390
https://reviews.llvm.org/D31010
Modified:
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h
llvm/trunk/test/CodeGen/ARM/debug-info-s16-reg.ll
llvm/trunk/test/CodeGen/ARM/debug-info-sreg2.ll
llvm/trunk/test/DebugInfo/ARM/s-super-register.ll
llvm/trunk/test/DebugInfo/X86/PR26148.ll
llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll
llvm/trunk/test/DebugInfo/X86/dbg-value-regmask-clobber.ll
llvm/trunk/test/DebugInfo/X86/dw_op_minus_direct.ll
llvm/trunk/test/DebugInfo/X86/fission-ranges.ll
llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll
llvm/trunk/test/DebugInfo/X86/subreg.ll
llvm/trunk/test/DebugInfo/X86/subregisters.ll
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp Thu Mar 16 12:14:56 2017
@@ -66,6 +66,12 @@ void DwarfExpression::AddShr(unsigned Sh
EmitOp(dwarf::DW_OP_shr);
}
+void DwarfExpression::AddAnd(unsigned Mask) {
+ EmitOp(dwarf::DW_OP_constu);
+ EmitUnsigned(Mask);
+ EmitOp(dwarf::DW_OP_and);
+}
+
bool DwarfExpression::AddMachineRegIndirect(const TargetRegisterInfo &TRI,
unsigned MachineReg, int Offset) {
if (isFrameRegister(TRI, MachineReg)) {
@@ -230,6 +236,12 @@ void DwarfExpression::AddExpression(DIEx
unsigned FragmentOffsetInBits) {
while (ExprCursor) {
auto Op = ExprCursor.take();
+
+ // If we need to mask out a subregister, do it now, unless the next
+ // operation would emit an OpPiece anyway.
+ if (SubRegisterSizeInBits && Op->getOp() != dwarf::DW_OP_LLVM_fragment)
+ maskSubRegister();
+
switch (Op->getOp()) {
case dwarf::DW_OP_LLVM_fragment: {
unsigned SizeInBits = Op->getArg(1);
@@ -285,9 +297,24 @@ void DwarfExpression::AddExpression(DIEx
}
}
+/// Add masking operations to stencil out a subregister.
+void DwarfExpression::maskSubRegister() {
+ assert(SubRegisterSizeInBits && "no subregister was registered");
+ if (SubRegisterOffsetInBits > 0)
+ AddShr(SubRegisterOffsetInBits);
+ uint64_t Mask = (1UL << SubRegisterSizeInBits) - 1;
+ AddAnd(Mask);
+}
+
+
void DwarfExpression::finalize() {
- if (SubRegisterSizeInBits)
- AddOpPiece(SubRegisterSizeInBits, SubRegisterOffsetInBits);
+ // Emit any outstanding DW_OP_piece operations to mask out subregisters.
+ if (SubRegisterSizeInBits == 0)
+ return;
+ // Don't emit a DW_OP_piece for a subregister at offset 0.
+ if (SubRegisterOffsetInBits == 0)
+ return;
+ AddOpPiece(SubRegisterSizeInBits, SubRegisterOffsetInBits);
}
void DwarfExpression::addFragmentOffset(const DIExpression *Expr) {
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h Thu Mar 16 12:14:56 2017
@@ -99,6 +99,9 @@ protected:
SubRegisterOffsetInBits = OffsetInBits;
}
+ /// Add masking operations to stencil out a subregister.
+ void maskSubRegister();
+
public:
DwarfExpression(unsigned DwarfVersion) : DwarfVersion(DwarfVersion) {}
virtual ~DwarfExpression() {};
@@ -126,8 +129,10 @@ public:
/// is at the top of the DWARF stack.
void AddOpPiece(unsigned SizeInBits, unsigned OffsetInBits = 0);
- /// Emit a shift-right dwarf expression.
+ /// Emit a shift-right dwarf operation.
void AddShr(unsigned ShiftBy);
+ /// Emit a bitwise and dwarf operation.
+ void AddAnd(unsigned Mask);
/// Emit a DW_OP_stack_value, if supported.
///
Modified: llvm/trunk/test/CodeGen/ARM/debug-info-s16-reg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/debug-info-s16-reg.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/debug-info-s16-reg.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/debug-info-s16-reg.ll Thu Mar 16 12:14:56 2017
@@ -3,8 +3,6 @@
; Test dwarf reg no for s16
;CHECK: super-register DW_OP_regx
;CHECK-NEXT: 264
-;CHECK-NEXT: DW_OP_piece
-;CHECK-NEXT: 4
target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:32-f32:32:32-f64:32:32-v64:32:64-v128:32:128-a0:0:32-n32"
target triple = "thumbv7-apple-macosx10.6.7"
Modified: llvm/trunk/test/CodeGen/ARM/debug-info-sreg2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/debug-info-sreg2.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/debug-info-sreg2.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/debug-info-sreg2.ll Thu Mar 16 12:14:56 2017
@@ -10,7 +10,7 @@ target triple = "thumbv7-apple-macosx10.
; CHECK: 0x00000000: Beginning address offset:
; CHECK-NEXT: Ending address offset:
-; CHECK-NEXT: Location description: 90 {{.. .. .. .. $}}
+; CHECK-NEXT: Location description: 90 {{.. .. $}}
define void @_Z3foov() optsize ssp !dbg !1 {
entry:
Modified: llvm/trunk/test/DebugInfo/ARM/s-super-register.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/ARM/s-super-register.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/ARM/s-super-register.ll (original)
+++ llvm/trunk/test/DebugInfo/ARM/s-super-register.ll Thu Mar 16 12:14:56 2017
@@ -5,9 +5,7 @@ target triple = "thumbv7-apple-macosx10.
; The S registers on ARM are expressed as pieces of their super-registers in DWARF.
;
; 0x90 DW_OP_regx of super-register
-; 0x93 DW_OP_piece
-; 0x9d DW_OP_bit_piece
-; CHECK: Location description: 90 {{.. .. ((93 ..)|(9d .. ..)) $}}
+; CHECK: Location description: 90
define void @_Z3foov() optsize ssp !dbg !1 {
entry:
Modified: llvm/trunk/test/DebugInfo/X86/PR26148.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/PR26148.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/PR26148.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/PR26148.ll Thu Mar 16 12:14:56 2017
@@ -19,7 +19,7 @@
; AS in 26163, we expect two ranges (as opposed to one), the first one being zero sized
;
;
-; CHECK: 0x00000025: Beginning address offset: 0x0000000000000004
+; CHECK: Beginning address offset: 0x0000000000000004
; CHECK: Ending address offset: 0x0000000000000004
; CHECK: Location description: 10 03 93 04 55 93 02
; constu 0x00000003, piece 0x00000004, rdi, piece 0x00000002
Modified: llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll Thu Mar 16 12:14:56 2017
@@ -34,10 +34,10 @@
; CHECK: Beginning address offset: [[C1]]
; CHECK: Ending address offset: [[C2:.*]]
; CHECK: Location description: 11 07
-; rax, piece 0x00000004
+; rax
; CHECK: Beginning address offset: [[C2]]
; CHECK: Ending address offset: [[R1:.*]]
-; CHECK: Location description: 50 93 04
+; CHECK: Location description: 50
; rdi+0
; CHECK: Beginning address offset: [[R1]]
; CHECK: Ending address offset: [[R2:.*]]
Modified: llvm/trunk/test/DebugInfo/X86/dbg-value-regmask-clobber.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dbg-value-regmask-clobber.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/dbg-value-regmask-clobber.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/dbg-value-regmask-clobber.ll Thu Mar 16 12:14:56 2017
@@ -16,10 +16,8 @@
; ASM: .Ldebug_loc1:
; ASM-NEXT: .quad .Lfunc_begin0-.Lfunc_begin0
; ASM-NEXT: .quad [[argc_range_end]]-.Lfunc_begin0
-; ASM-NEXT: .short 3 # Loc expr size
+; ASM-NEXT: .short 1 # Loc expr size
; ASM-NEXT: .byte 82 # super-register DW_OP_reg2
-; ASM-NEXT: .byte 147 # DW_OP_piece
-; ASM-NEXT: .byte 4 # 4
; argc is the first formal parameter.
; DWARF: .debug_info contents:
@@ -30,7 +28,7 @@
; DWARF: .debug_loc contents:
; DWARF: [[argc_loc_offset]]: Beginning address offset: 0x0000000000000000
; DWARF-NEXT: Ending address offset: 0x0000000000000013
-; DWARF-NEXT: Location description: 52 93 04
+; DWARF-NEXT: Location description: 52
; ModuleID = 't.cpp'
source_filename = "test/DebugInfo/X86/dbg-value-regmask-clobber.ll"
Modified: llvm/trunk/test/DebugInfo/X86/dw_op_minus_direct.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dw_op_minus_direct.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/dw_op_minus_direct.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/dw_op_minus_direct.ll Thu Mar 16 12:14:56 2017
@@ -8,8 +8,8 @@
; CHECK: Beginning address offset: 0x0000000000000000
; CHECK: Ending address offset: 0x0000000000000004
-; CHECK: Location description: 50 10 01 1c 93 04
-; rax, constu 0x00000001, minus, piece 0x00000004
+; CHECK: Location description: 50 10 ff ff ff ff 0f 1a 10 01 1c
+; rax, constu 0xffffffff, and, constu 0x00000001, minus
source_filename = "minus.c"
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.12.0"
Modified: llvm/trunk/test/DebugInfo/X86/fission-ranges.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/fission-ranges.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/fission-ranges.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/fission-ranges.ll Thu Mar 16 12:14:56 2017
@@ -30,16 +30,16 @@
; CHECK-NEXT: {{^$}}
; CHECK-NEXT: Beginning address index: 3
; CHECK-NEXT: Length: 25
-; CHECK-NEXT: Location description: 50 93 04
+; CHECK-NEXT: Location description: 50
; CHECK: [[E]]: Beginning address index: 4
; CHECK-NEXT: Length: 19
-; CHECK-NEXT: Location description: 50 93 04
+; CHECK-NEXT: Location description: 50
; CHECK: [[B]]: Beginning address index: 5
; CHECK-NEXT: Length: 17
-; CHECK-NEXT: Location description: 50 93 04
+; CHECK-NEXT: Location description: 50
; CHECK: [[D]]: Beginning address index: 6
; CHECK-NEXT: Length: 17
-; CHECK-NEXT: Location description: 50 93 04
+; CHECK-NEXT: Location description: 50
; Make sure we don't produce any relocations in any .dwo section (though in particular, debug_info.dwo)
; HDR-NOT: .rela.{{.*}}.dwo
Modified: llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll Thu Mar 16 12:14:56 2017
@@ -8,8 +8,8 @@
; CHECK-NEXT: DW_AT_location [DW_FORM_data4]
; CHECK-NEXT: DW_AT_name{{.*}}"a"
; CHECK: .debug_loc contents:
-; rax, piece 0x00000004
-; CHECK: Location description: 50 93 04
+; rax
+; CHECK: Location description: 50
; SANITY: DBG_VALUE
; SANITY-NOT: DBG_VALUE
; ModuleID = 'test.ll'
Modified: llvm/trunk/test/DebugInfo/X86/subreg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/subreg.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/subreg.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/subreg.ll Thu Mar 16 12:14:56 2017
@@ -4,8 +4,9 @@
; being in its superregister.
; CHECK: .byte 80 # super-register DW_OP_reg0
-; CHECK-NEXT: .byte 147 # DW_OP_piece
-; CHECK-NEXT: .byte 2 # 2
+; No need to a piece at offset 0.
+; CHECK-NOT: DW_OP_piece
+; CHECK-NOT: DW_OP_bit_piece
define i16 @f(i16 signext %zzz) nounwind !dbg !1 {
entry:
Modified: llvm/trunk/test/DebugInfo/X86/subregisters.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/subregisters.ll?rev=297965&r1=297964&r2=297965&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/subregisters.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/subregisters.ll Thu Mar 16 12:14:56 2017
@@ -2,7 +2,7 @@
; RUN: llvm-dwarfdump %t.o | FileCheck %s
;
; Test that on x86_64, the 32-bit subregister esi is emitted as
-; DW_OP_piece 32 of the 64-bit rsi.
+; subregister of the 64-bit rsi.
;
; rdar://problem/16015314
;
@@ -11,8 +11,8 @@
; CHECK-NEXT: DW_AT_location [DW_FORM_data4] (0x00000000)
; CHECK-NEXT: DW_AT_name [DW_FORM_strp]{{.*}} "a"
; CHECK: .debug_loc contents:
-; rsi, piece 0x00000004
-; CHECK: Location description: 54 93 04
+; rsi
+; CHECK: Location description: 54
;
; struct bar {
; int a;
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