[llvm] [InstrRef] Skip clobbered EntryValue register recovery (PR #77938)
Felipe de Azevedo Piovezan via llvm-commits
llvm-commits at lists.llvm.org
Fri Jan 12 07:35:12 PST 2024
https://github.com/felipepiovezan updated https://github.com/llvm/llvm-project/pull/77938
>From ed7b297632b8edaa79cd81e63110f6b2983316be Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiovezan at apple.com>
Date: Thu, 11 Jan 2024 14:25:34 -0300
Subject: [PATCH] [InstrRef] Skip clobbered EntryValue register recovery
This changes the final stage of InstrRef, i.e. the TransferTracker (which
combines the values locations with the variable values), so that it treats a
DEBUG_VALUE of an EntryValue just like a DEBUG_VALUE of a constant: a location
that is never clobbered and can be propagated to subsequent BBs as long as no
other DEBUG_VALUE intrinsics updated the variable.
We add two tests here:
1. `entry_value_clobbered_stack_copy` that saves a register on the stack, uses
this register as an entry value DBG_VALUE location, and then clobbers it. Prior
to this patch, this test would crash because we would try to describe a new
location for the variable in terms of what was saved on the stack, and use an
invalid expression to do so. This is not needed as an EntryValue can never be
clobbered.
2. `entry_value_gets_propagated`, that tests that an EntryValue DBG_VALUE is
propagated in a diamond-shaped CFG. This test works with or without this patch,
but it reveals a bug (see the FIXME), where the propagation doesn't happen if
the register gets clobbered. This same test (with the clobbered register) works
fine in the VarLoc implementation of LDV.
---
.../LiveDebugValues/InstrRefBasedImpl.cpp | 2 +-
.../entry_value_clobbered_stack_copy.mir | 53 +++++++++
.../InstrRef/entry_value_gets_propagated.mir | 102 ++++++++++++++++++
3 files changed, 156 insertions(+), 1 deletion(-)
create mode 100644 llvm/test/DebugInfo/MIR/InstrRef/entry_value_clobbered_stack_copy.mir
create mode 100644 llvm/test/DebugInfo/MIR/InstrRef/entry_value_gets_propagated.mir
diff --git a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
index cfc8c28b99e562..c0082b580c15d0 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
@@ -669,7 +669,7 @@ class TransferTracker {
DbgValueProperties Properties(MI);
// Ignore non-register locations, we don't transfer those.
- if (MI.isUndefDebugValue() ||
+ if (MI.isUndefDebugValue() || MI.getDebugExpression()->isEntryValue() ||
all_of(MI.debug_operands(),
[](const MachineOperand &MO) { return !MO.isReg(); })) {
auto It = ActiveVLocs.find(Var);
diff --git a/llvm/test/DebugInfo/MIR/InstrRef/entry_value_clobbered_stack_copy.mir b/llvm/test/DebugInfo/MIR/InstrRef/entry_value_clobbered_stack_copy.mir
new file mode 100644
index 00000000000000..1280045a0a1cf1
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/InstrRef/entry_value_clobbered_stack_copy.mir
@@ -0,0 +1,53 @@
+# RUN: llc --run-pass=livedebugvalues -o - %s | FileCheck %s
+# REQUIRES: x86-registered-target
+
+--- |
+ target triple = "x86_64-"
+ define void @foo(ptr swiftasync %0) !dbg !4 {
+ call void @llvm.dbg.value(metadata ptr %0, metadata !9, metadata !DIExpression(DW_OP_LLVM_entry_value, 1)), !dbg !17
+ ret void
+ }
+ declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+ !llvm.module.flags = !{!0}
+ !llvm.dbg.cu = !{!1}
+
+ !0 = !{i32 2, !"Debug Info Version", i32 3}
+ !1 = distinct !DICompileUnit(language: DW_LANG_Swift, file: !2, producer: "blah", isOptimized: true, flags: "blah", runtimeVersion: 5, emissionKind: FullDebug)
+ !2 = !DIFile(filename: "blah", directory: "blah")
+ !3 = !{}
+ !4 = distinct !DISubprogram(name: "blah", linkageName: "blah", scope: !2, file: !2, line: 284, type: !7, unit: !1)
+ !7 = !DISubroutineType(types: !3)
+ !9 = !DILocalVariable(name: "self", arg: 3, scope: !4, file: !2, line: 328, type: !12, flags: DIFlagArtificial)
+ !12 = !DICompositeType(tag: DW_TAG_structure_type, name: "blah", scope: !2, file: !2, size: 64, elements: !3)
+ !17 = !DILocation(line: 328, column: 17, scope: !4)
+
+...
+---
+name: foo
+alignment: 16
+debugInstrRef: true
+tracksDebugUserValues: true
+liveins:
+ - { reg: '$r14', virtual-reg: '' }
+stack:
+ - { id: 0, name: '', type: spill-slot, offset: -64, size: 8, alignment: 8,
+ stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+body: |
+ bb.0:
+ liveins: $r14
+
+ ; Put a copy of r14 on the stack.
+ MOV64mr $rbp, 1, $noreg, -48, $noreg, $r14 :: (store (s64) into %stack.0)
+ DBG_VALUE $r14, $noreg, !9, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location !17
+ MOV64mi32 $noreg, 1, $noreg, 0, $noreg, 0, debug-location !17 :: (store (s64) into `ptr null`)
+ $r14 = MOV64rr killed $r13
+ ; Clobber $r14
+ RETI64 24
+
+# CHECK: bb.0:
+# CHECK: MOV64mr $rbp, 1, $noreg, -48, $noreg, $r14
+# CHECK-NEXT: DBG_VALUE $r14, {{.*}}, !DIExpression(DW_OP_LLVM_entry_value, 1)
+# CHECK-NOT: DBG_VALUE
+...
diff --git a/llvm/test/DebugInfo/MIR/InstrRef/entry_value_gets_propagated.mir b/llvm/test/DebugInfo/MIR/InstrRef/entry_value_gets_propagated.mir
new file mode 100644
index 00000000000000..4fa1485a75d2ce
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/InstrRef/entry_value_gets_propagated.mir
@@ -0,0 +1,102 @@
+# RUN: llc --run-pass=livedebugvalues -o - %s | FileCheck %s
+# REQUIRES: x86-registered-target
+--- |
+ target triple = "x86_64-"
+
+ define i32 @baz(i32 swiftasync %arg1, i32 noundef %arg2, i1 %cond) !dbg !9 {
+ tail call void @llvm.dbg.value(metadata i32 %arg1, metadata !17, metadata !DIExpression(DW_OP_LLVM_entry_value, 1)), !dbg !19
+ br i1 %cond, label %if.then, label %if.else, !dbg !22
+ if.then:
+ %call = call i32 @foo(i32 noundef %arg1), !dbg !23
+ br label %if.end, !dbg !25
+ if.else:
+ %call1 = call i32 @foo(i32 noundef %arg2), !dbg !26
+ br label %if.end
+ if.end:
+ %temp.0 = phi i32 [ %call, %if.then ], [ %call1, %if.else ], !dbg !28
+ ret i32 %temp.0, !dbg !29
+ }
+
+ declare i32 @foo(i32)
+ declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+ !llvm.dbg.cu = !{!0}
+ !llvm.module.flags = !{!2, !3}
+
+ !0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "ha", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+ !1 = !DIFile(filename: "test.c", directory: "hah")
+ !2 = !{i32 7, !"Dwarf Version", i32 4}
+ !3 = !{i32 2, !"Debug Info Version", i32 3}
+ !9 = distinct !DISubprogram(name: "baz", scope: !1, file: !1, line: 3, type: !10, scopeLine: 3, unit: !0, retainedNodes: !13)
+ !10 = !DISubroutineType(types: !11)
+ !11 = !{!12, !12, !12, !12}
+ !12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+ !13 = !{!14, !15, !16, !17}
+ !14 = !DILocalVariable(name: "arg1", arg: 1, scope: !9, file: !1, line: 3, type: !12)
+ !15 = !DILocalVariable(name: "arg2", arg: 2, scope: !9, file: !1, line: 3, type: !12)
+ !16 = !DILocalVariable(name: "cond", arg: 3, scope: !9, file: !1, line: 3, type: !12)
+ !17 = !DILocalVariable(name: "local", scope: !9, file: !1, line: 4, type: !12)
+ !19 = !DILocation(line: 0, scope: !9)
+ !20 = !DILocation(line: 7, column: 7, scope: !21)
+ !21 = distinct !DILexicalBlock(scope: !9, file: !1, line: 7, column: 7)
+ !22 = !DILocation(line: 7, column: 7, scope: !9)
+ !23 = !DILocation(line: 8, column: 12, scope: !24)
+ !24 = distinct !DILexicalBlock(scope: !21, file: !1, line: 7, column: 13)
+ !25 = !DILocation(line: 9, column: 3, scope: !24)
+ !26 = !DILocation(line: 10, column: 12, scope: !27)
+ !27 = distinct !DILexicalBlock(scope: !21, file: !1, line: 9, column: 10)
+ !28 = !DILocation(line: 0, scope: !21)
+ !29 = !DILocation(line: 13, column: 3, scope: !9)
+
+...
+---
+name: baz
+alignment: 16
+debugInstrRef: true
+tracksDebugUserValues: true
+liveins:
+ - { reg: '$r14', virtual-reg: '' }
+ - { reg: '$edi', virtual-reg: '' }
+ - { reg: '$esi', virtual-reg: '' }
+ - { reg: '$edx', virtual-reg: '' }
+body: |
+ bb.0:
+ successors: %bb.2(0x40000000), %bb.1(0x40000000)
+ liveins: $r14, $edi, $edx, $esi
+
+ DBG_VALUE $r14, $noreg, !14, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location !19
+ ; FIXME: InstrRef is not yet capable of propagating these when the entry
+ ; value register is clobbered.
+ ;$r14 = MOV64ri 0, debug-location !20
+ CMP32ri killed renamable $edx, 0, implicit-def $eflags, debug-location !20
+ JCC_1 %bb.2, 4, implicit killed $eflags, debug-location !22
+
+ bb.1.if.then:
+ successors: %bb.3(0x80000000)
+ liveins: $edi, $r13
+
+ CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit-def $eax, debug-location !23
+ JMP_1 %bb.3, debug-location !25
+
+ bb.2.if.else:
+ successors: %bb.3(0x80000000)
+ liveins: $esi, $r13
+
+ $edi = MOV32rr killed $esi, debug-location !26
+ CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit-def $eax, debug-location !26
+
+ bb.3.if.end:
+ liveins: $eax
+
+ $rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !29
+ RET64 implicit $eax, debug-location !29
+
+# CHECK-LABEL: bb.0:
+# CHECK: DBG_VALUE $r14, {{.*}}, !DIExpression(DW_OP_LLVM_entry_value, 1)
+# CHECK-LABEL: bb.1.if.then:
+# CHECK: DBG_VALUE $r14, {{.*}}, !DIExpression(DW_OP_LLVM_entry_value, 1)
+# CHECK-LABEL: bb.2.if.else:
+# CHECK: DBG_VALUE $r14, {{.*}}, !DIExpression(DW_OP_LLVM_entry_value, 1)
+# CHECK-LABEL: bb.3.if.end:
+# CHECK: DBG_VALUE $r14, {{.*}}, !DIExpression(DW_OP_LLVM_entry_value, 1)
+...
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