[llvm] cc1e87b - [DebugInfo][InstrRef] Avoid stack-slot-coloring changing codegen due to DI
Jeremy Morse via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 25 04:32:27 PDT 2021
Author: Jeremy Morse
Date: 2021-08-25T12:04:59+01:00
New Revision: cc1e87bf55e73e769e96e6cc3fcfc69f88d94097
URL: https://github.com/llvm/llvm-project/commit/cc1e87bf55e73e769e96e6cc3fcfc69f88d94097
DIFF: https://github.com/llvm/llvm-project/commit/cc1e87bf55e73e769e96e6cc3fcfc69f88d94097.diff
LOG: [DebugInfo][InstrRef] Avoid stack-slot-coloring changing codegen due to DI
Stack slot colouring adds "weight" to slots if a non-dbg-value instruction
refers to it. This, unfortunately, means that DBG_PHI instructions can have
an effect on codegen. The fix is very simple, replace isDebugValue with
isDebugInstr.
The regression test contains a scenario that reproduces this problem; I've
represented both normal-debug mode and instr-ref debug mode instructions
in comment lines prefixed with AAAAAA and BBBBBB, and un-comment them with
sed to test that the two different modes produce the same behaviour.
Differential Revision: https://reviews.llvm.org/D108627
Added:
llvm/test/DebugInfo/MIR/InstrRef/stack-coloring-dbg-phi.mir
Modified:
llvm/lib/CodeGen/StackSlotColoring.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/StackSlotColoring.cpp b/llvm/lib/CodeGen/StackSlotColoring.cpp
index ebe00bd7402fa..9aea5a7a8853b 100644
--- a/llvm/lib/CodeGen/StackSlotColoring.cpp
+++ b/llvm/lib/CodeGen/StackSlotColoring.cpp
@@ -169,7 +169,7 @@ void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
if (!LS->hasInterval(FI))
continue;
LiveInterval &li = LS->getInterval(FI);
- if (!MI.isDebugValue())
+ if (!MI.isDebugInstr())
li.incrementWeight(
LiveIntervals::getSpillWeight(false, true, MBFI, MI));
}
diff --git a/llvm/test/DebugInfo/MIR/InstrRef/stack-coloring-dbg-phi.mir b/llvm/test/DebugInfo/MIR/InstrRef/stack-coloring-dbg-phi.mir
new file mode 100644
index 0000000000000..d9540a7eb4b08
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/InstrRef/stack-coloring-dbg-phi.mir
@@ -0,0 +1,294 @@
+# RUN: sed 's_;AAAAAA __' < %s \
+# RUN: | llc -x mir -o - -start-before=phi-node-elimination \
+# RUN: -stop-after=stack-slot-coloring -simplify-mir \
+# RUN: -experimental-debug-variable-locations=true \
+# RUN: | FileCheck %s --check-prefix=DBGPHIS
+# RUN: sed 's_;BBBBBB __' < %s \
+# RUN: | llc -x mir -o - -start-before=phi-node-elimination \
+# RUN: -stop-after=stack-slot-coloring -simplify-mir \
+# RUN: -experimental-debug-variable-locations=false \
+# RUN: | FileCheck %s --check-prefix=DBGVALS
+#
+# Test that DBG_PHI instructions do not add "weight" to stack slots and cause
+# their coalescing / coloring to change. This is hard to trigger, because it's
+# closely coupled with the register allocator. Thus, the test is very
+# complicated and hard to reduce.
+#
+# In block 13 there are two implementations of variable location tracking, but
+# both are commented out. Use sed in the command lines above to un-comment
+# each one and test what it does: in each case, the PHI should occur in
+# %stack.4 rather than anywhere else.
+#
+# Future register allocator changes might change the slot; in that case, just
+# update the slot number, so long as it's the same between each RUN.
+#
+# DBGPHIS: DBG_PHI %stack.4,
+# DBGVALS: DBG_VALUE %stack.4,
+
+--- |
+ 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"
+
+ define hidden fastcc i64 @amd64_push_arguments(i32 *%regcache, i32 *%args) unnamed_addr !dbg !4 {
+ ret i64 0
+ }
+
+ ; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+ declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+ !llvm.module.flags = !{!0, !1}
+ !llvm.dbg.cu = !{!2}
+
+ !0 = !{i32 2, !"Debug Info Version", i32 3}
+ !1 = !{i32 2, !"Dwarf Version", i32 4}
+ !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "beards", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+ !3 = !DIFile(filename: "bees.cpp", directory: ".")
+ !4 = distinct !DISubprogram(name: "nope", scope: !3, file: !3, line: 1, type: !5, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !8)
+ !5 = !DISubroutineType(types: !6)
+ !6 = !{!7}
+ !7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+ !8 = !{}
+ !9 = !DILocation(line: 0, scope: !4)
+ !10 = !DILocalVariable(name: "flannel", scope: !4, file: !3, line: 1, type: !7)
+...
+---
+name: amd64_push_arguments
+alignment: 16
+tracksRegLiveness: true
+registers:
+ - { id: 0, class: gr32 }
+ - { id: 1, class: gr32 }
+ - { id: 2, class: gr32 }
+ - { id: 3, class: gr64 }
+ - { id: 4, class: gr32 }
+ - { id: 5, class: gr32 }
+ - { id: 6, class: gr32 }
+ - { id: 7, class: gr32 }
+ - { id: 8, class: gr64 }
+ - { id: 9, class: gr32 }
+ - { id: 10, class: gr32 }
+ - { id: 11, class: gr64 }
+ - { id: 12, class: gr32 }
+ - { id: 13, class: gr64 }
+ - { id: 14, class: gr32 }
+ - { id: 15, class: gr64 }
+ - { id: 16, class: gr64 }
+ - { id: 17, class: gr64 }
+ - { id: 18, class: gr32 }
+ - { id: 19, class: gr8 }
+ - { id: 20, class: gr64 }
+ - { id: 21, class: gr32 }
+ - { id: 22, class: gr32 }
+ - { id: 23, class: gr8 }
+ - { id: 24, class: gr32 }
+ - { id: 25, class: gr32 }
+ - { id: 26, class: gr32 }
+ - { id: 27, class: gr32 }
+ - { id: 28, class: gr8 }
+ - { id: 29, class: gr32 }
+ - { id: 30, class: gr8 }
+ - { id: 31, class: gr32 }
+ - { id: 32, class: gr32 }
+ - { id: 33, class: gr32 }
+ - { id: 34, class: gr8 }
+ - { id: 35, class: gr32 }
+ - { id: 36, class: gr64 }
+ - { id: 37, class: gr32 }
+ - { id: 38, class: gr32 }
+ - { id: 39, class: gr8 }
+ - { id: 40, class: gr32 }
+ - { id: 41, class: gr8 }
+ - { id: 42, class: gr32 }
+ - { id: 43, class: gr32 }
+ - { id: 44, class: gr64_nosp }
+ - { id: 45, class: gr64 }
+ - { id: 46, class: gr32 }
+ - { id: 47, class: gr64 }
+ - { id: 48, class: gr32 }
+ - { id: 49, class: gr32 }
+ - { id: 50, class: gr64 }
+ - { id: 51, class: gr64 }
+ - { id: 52, class: gr64 }
+ - { id: 53, class: gr64 }
+ - { id: 54, class: gr32 }
+ - { id: 55, class: gr64 }
+ - { id: 56, class: gr32 }
+liveins:
+ - { reg: '$rdi', virtual-reg: '%15' }
+frameInfo:
+ maxAlignment: 8
+ hasCalls: true
+stack:
+ - { id: 0, size: 8, alignment: 8 }
+ - { id: 1, type: variable-sized, alignment: 1 }
+machineFunctionInfo: {}
+body: |
+ bb.0:
+ successors: %bb.2(0x00000800), %bb.1(0x7ffff800)
+ liveins: $rdi
+
+ %15:gr64 = COPY killed $rdi
+ ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !9
+ ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !9
+ %18:gr32 = MOV32r0 implicit-def dead $eflags
+ %19:gr8 = COPY killed %18.sub_8bit
+ TEST8rr killed %19, %19, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.2, 5, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.1, debug-location !9
+
+ bb.1:
+ RET 0, undef $rax
+
+ bb.2:
+ %27:gr32 = MOV32r0 implicit-def dead $eflags
+ %50:gr64 = LEA64r %stack.0, 1, $noreg, 0, $noreg
+ %54:gr32 = MOV32ri 8
+
+ bb.3:
+ successors: %bb.4, %bb.5
+
+ %0:gr32 = PHI undef %21:gr32, %bb.2, %0, %bb.5, %0, %bb.6, %0, %bb.8, %0, %bb.10, %10, %bb.21
+ %23:gr8 = COPY %27.sub_8bit
+ TEST8rr killed %23, %23, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.5, 5, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.4, debug-location !9
+
+ bb.4:
+ %24:gr32 = MOV32ri 1
+
+ bb.5:
+ successors: %bb.3(0x20000000), %bb.6(0x60000000)
+
+ %1:gr32 = PHI %27, %bb.3, %24, %bb.4, debug-location !9
+ %25:gr32 = nsw ADD32rr %1, %0, implicit-def dead $eflags, debug-location !9
+ CMP32ri8 killed %25, 6, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.3, 7, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.6, debug-location !9
+
+ bb.6:
+ successors: %bb.3(0x2aaaaaab), %bb.7(0x55555555)
+
+ %28:gr8 = COPY %27.sub_8bit
+ TEST8rr killed %28, %28, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.3, 5, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.7, debug-location !9
+
+ bb.7:
+ successors: %bb.8(0x60000000), %bb.9(0x20000000)
+
+ TEST32rr killed %1, %1, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.9, 5, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.8, debug-location !9
+
+ bb.8:
+ successors: %bb.3(0x55555555), %bb.9(0x2aaaaaab)
+
+ %30:gr8 = COPY %27.sub_8bit
+ TEST8rr killed %30, %30, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.3, 5, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.9, debug-location !9
+
+ bb.9:
+ successors: %bb.10(0x80000000), %bb.12(0x00000000)
+
+ CMP32ri8 undef %32:gr32, 16, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.12, 15, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.10, debug-location !9
+
+ bb.10:
+ successors: %bb.11, %bb.3
+
+ %34:gr8 = COPY %27.sub_8bit
+ TEST8rr killed %34, %34, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.3, 5, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.11, debug-location !9
+
+ bb.11:
+ %36:gr64 = SUBREG_TO_REG 0, %27, %subreg.sub_32bit
+ JMP_1 %bb.13, debug-location !9
+
+ bb.12:
+ successors:
+
+
+ bb.13:
+ successors: %bb.18(0x2aaaaaab), %bb.14(0x55555555)
+
+ %2:gr32 = PHI undef %35:gr32, %bb.11, %14, %bb.21
+ %3:gr64 = PHI %36, %bb.11, %13, %bb.21
+ ;AAAAAA %4:gr32 = PHI %0, %bb.11, %10, %bb.21, debug-instr-number 1
+ ;BBBBBB %4:gr32 = PHI %0, %bb.11, %10, %bb.21
+ %5:gr32 = PHI undef %35:gr32, %bb.11, %9, %bb.21
+ ;AAAAAA DBG_INSTR_REF 1, 0, !10, !DIExpression(), debug-location !9
+ ;BBBBBB DBG_VALUE %4, 0, !10, !DIExpression(), debug-location !9
+ %39:gr8 = COPY %27.sub_8bit
+ TEST8rr killed %39, %39, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.18, 5, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.14, debug-location !9
+
+ bb.14:
+ successors: %bb.17(0x40000001), %bb.15(0x3fffffff)
+
+ %41:gr8 = COPY %27.sub_8bit
+ TEST8rr killed %41, %41, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.17, 5, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.15, debug-location !9
+
+ bb.15:
+
+ bb.16:
+ %6:gr32 = nsw INC32r killed %4, implicit-def dead $eflags, debug-location !9
+ %48:gr32 = MOV32r0 implicit-def dead $eflags
+ JMP_1 %bb.21, debug-location !9
+
+ bb.17:
+ %7:gr32 = nsw INC32r killed %5, implicit-def dead $eflags, debug-location !9
+ %46:gr32 = MOV32r0 implicit-def dead $eflags
+ JMP_1 %bb.21, debug-location !9
+
+ bb.18:
+ successors: %bb.20(0x80000000), %bb.19(0x00000000)
+
+ TEST32rr %5, %5, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.20, 15, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.19, debug-location !9
+
+ bb.19:
+ successors:
+
+
+ bb.20:
+ %43:gr32 = nsw DEC32r %5, implicit-def dead $eflags, debug-location !9
+ %44:gr64_nosp = SUBREG_TO_REG 0, killed %43, %subreg.sub_32bit
+ ; Fiddled with to morph into llvm test,
+ %8:gr64 = LEA64r $noreg, 4, killed %44, @amd64_push_arguments, $noreg, debug-location !9
+ %42:gr32 = MOV32ri 8
+ JMP_1 %bb.21, debug-location !9
+
+ bb.21:
+ successors: %bb.13(0x7c000000), %bb.3(0x04000000)
+
+ %9:gr32 = PHI %5, %bb.20, %7, %bb.17, %5, %bb.16, debug-location !9
+ %10:gr32 = PHI %4, %bb.20, %4, %bb.17, %6, %bb.16, debug-location !9
+ %11:gr64 = PHI %8, %bb.20, undef %45:gr64, %bb.17, undef %47:gr64, %bb.16
+ %12:gr32 = PHI %42, %bb.20, %46, %bb.17, %48, %bb.16, debug-location !9
+ %49:gr32 = MOV32rm killed %11, 1, $noreg, 0, $noreg, debug-location !9 :: (load (s32) from `i32 *undef`)
+ ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !9
+ $rdi = COPY %50, debug-location !9
+ CALL64pcrel32 target-flags(x86-plt) &memcpy, csr_64, implicit $rsp, implicit $ssp, implicit killed $rdi, implicit undef $rsi, implicit undef $rdx, implicit-def $rsp, implicit-def $ssp, implicit-def dead $rax, debug-location !9
+ ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !9
+ ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !9
+ $rdi = COPY %15, debug-location !9
+ $esi = COPY killed %49, debug-location !9
+ $edx = COPY killed %12, debug-location !9
+ $ecx = COPY %54, debug-location !9
+ $r8 = COPY %50, debug-location !9
+ CALL64r undef %55:gr64, csr_64, implicit $rsp, implicit $ssp, implicit killed $rdi, implicit killed $esi, implicit killed $edx, implicit killed $ecx, implicit killed $r8, implicit-def $rsp, implicit-def $ssp, debug-location !9
+ ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !9
+ %13:gr64 = nuw nsw INC64r killed %3, implicit-def dead $eflags, debug-location !9
+ %14:gr32 = ADD32ri8 killed %2, -8, implicit-def dead $eflags, debug-location !9
+ CMP32ri8 %14, 8, implicit-def $eflags, debug-location !9
+ JCC_1 %bb.13, 15, implicit killed $eflags, debug-location !9
+ JMP_1 %bb.3, debug-location !9
+
+...
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