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llvm-project/llvm/test/Transforms/InstCombine/debuginfo-dce.ll
Shubham Sandeep Rastogi f4681be06b
Use DIExpression::foldConstantMath at the result of a Salvaged expression (#71721) 
This patch uses `DIExpression::foldConstantMath()` at the result of a
Salvaged expression, that is, it runs the folding optimizations after an
expression has been salvaged completely, to reduce how many times the
fold optimization function is called. Which should help in reducing the
size of DIExpressions that grow because of salvaging debug info

After checking the size of the dSYM with and without this change, I saw
a decrease of about 300KB, where the debug_loc section is about 1.6 GB
in size.

Where the debug loc section reduced in size by 212KB and it is 193MB in
size, the rest comes from the debug_info section

This is part of a stack of patches and comes after:
https://github.com/llvm/llvm-project/pull/69768
https://github.com/llvm/llvm-project/pull/71717
https://github.com/llvm/llvm-project/pull/71718
https://github.com/llvm/llvm-project/pull/71719
2024-05-29 16:25:02 -07:00

141 lines
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; RUN: opt -passes=instcombine %s -S -o - | FileCheck %s
; RUN: opt -passes=instcombine %s -S -o - --try-experimental-debuginfo-iterators | FileCheck %s
; Verify that the eliminated instructions (bitcast, gep, load) are salvaged into
; a DIExpression.
;
; Originally created from the following C source and then heavily isolated/reduced.
;
; struct entry {
; struct entry *next;
; };
; void scan(struct entry *queue, struct entry *end)
; {
; struct entry *entry;
; for (entry = (struct entry *)((char *)(queue->next) - 8);
; &entry->next == end;
; entry = (struct entry *)((char *)(entry->next) - 8)) {
; }
; }
; ModuleID = '<stdin>'
source_filename = "test.c"
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.12.0"
%struct.entry = type { ptr }
; This salvage can't currently occur safely (PR40628), however if/when that's
; ever fixed, then this is definitely a piece of test coverage that should
; be maintained.
define void @salvage_load(ptr %queue) local_unnamed_addr #0 !dbg !14 {
entry:
%im_not_dead = alloca ptr
%0 = load ptr, ptr %queue, align 8, !dbg !19
%1 = load ptr, ptr %queue, align 8, !dbg !19
call void @llvm.dbg.value(metadata ptr %1, metadata !18, metadata !20), !dbg !19
; CHECK: define void @salvage_load
; CHECK-NEXT: entry:
; CHECK-NEXT: call void @llvm.dbg.value(metadata ptr poison
store ptr %1, ptr %im_not_dead, align 8
ret void, !dbg !21
}
define void @salvage_bitcast(ptr %queue) local_unnamed_addr #0 !dbg !22 {
entry:
%im_not_dead = alloca ptr
call void @llvm.dbg.value(metadata ptr %queue, metadata !24, metadata !20), !dbg !23
; CHECK: define void @salvage_bitcast
; CHECK-NEXT: entry:
; CHECK-NEXT: call void @llvm.dbg.value(metadata ptr %queue,
; CHECK-SAME: metadata !DIExpression(DW_OP_plus_uconst, 0))
store ptr %queue, ptr %im_not_dead, align 8
ret void, !dbg !23
}
define void @salvage_gep0(ptr %queue, ptr %end) local_unnamed_addr #0 !dbg !25 {
entry:
%im_not_dead = alloca ptr
%0 = getelementptr inbounds %struct.entry, ptr %queue, i32 -1, i32 0, !dbg !26
%1 = getelementptr inbounds %struct.entry, ptr %queue, i32 -1, i32 0, !dbg !26
call void @llvm.dbg.value(metadata ptr %1, metadata !27, metadata !20), !dbg !26
; CHECK: define void @salvage_gep0
; CHECK-NEXT: entry:
; CHECK-NEXT: call void @llvm.dbg.value(metadata ptr %queue,
; CHECK-SAME: metadata !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_stack_value))
store ptr %1, ptr %im_not_dead, align 8
ret void, !dbg !26
}
define void @salvage_gep1(ptr %queue, ptr %end) local_unnamed_addr #0 !dbg !28 {
entry:
%im_not_dead = alloca ptr
%0 = getelementptr inbounds %struct.entry, ptr %queue, i32 -1, i32 0, !dbg !29
%1 = getelementptr inbounds %struct.entry, ptr %queue, i32 -1, i32 0, !dbg !29
call void @llvm.dbg.value(metadata ptr %1, metadata !30, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)), !dbg !29
; CHECK: define void @salvage_gep1
; CHECK-NEXT: entry:
; CHECK-NEXT: call void @llvm.dbg.value(metadata ptr %queue,
; CHECK-SAME: metadata !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32))
store ptr %1, ptr %im_not_dead, align 8
ret void, !dbg !29
}
define void @salvage_gep2(ptr %queue, ptr %end) local_unnamed_addr #0 !dbg !31 {
entry:
%im_not_dead = alloca ptr
%0 = getelementptr inbounds %struct.entry, ptr %queue, i32 -1, i32 0, !dbg !32
%1 = getelementptr inbounds %struct.entry, ptr %queue, i32 -1, i32 0, !dbg !32
call void @llvm.dbg.value(metadata ptr %1, metadata !33, metadata !DIExpression(DW_OP_stack_value)), !dbg !32
; CHECK: define void @salvage_gep2
; CHECK-NEXT: entry:
; CHECK-NEXT: call void @llvm.dbg.value(metadata ptr %queue,
; CHECK-SAME: metadata !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_stack_value))
store ptr %1, ptr %im_not_dead, align 8
ret void, !dbg !32
}
; Function Attrs: nounwind readnone
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
attributes #0 = { nounwind ssp uwtable }
attributes #1 = { nounwind readnone }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!10, !11, !12}
!llvm.ident = !{!13}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 5.0.0 (trunk 297628) (llvm/trunk 297643)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3)
!1 = !DIFile(filename: "test.c", directory: "/")
!2 = !{}
!3 = !{!4, !8}
!4 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 64)
!5 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "entry", file: !1, line: 1, size: 64, elements: !6)
!6 = !{!7}
!7 = !DIDerivedType(tag: DW_TAG_member, name: "next", scope: !5, file: !1, line: 2, baseType: !4, size: 64)
!8 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !9, size: 64)
!9 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
!10 = !{i32 2, !"Dwarf Version", i32 4}
!11 = !{i32 2, !"Debug Info Version", i32 3}
!12 = !{i32 1, !"PIC Level", i32 2}
!13 = !{!"clang version 5.0.0 (trunk 297628) (llvm/trunk 297643)"}
!14 = distinct !DISubprogram(name: "scan", scope: !1, file: !1, line: 4, type: !15, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !17)
!15 = !DISubroutineType(types: !16)
!16 = !{null, !4, !4}
!17 = !{!18}
!18 = !DILocalVariable(name: "entry", scope: !14, file: !1, line: 6, type: !4)
!19 = !DILocation(line: 6, column: 17, scope: !14)
!20 = !DIExpression(DW_OP_plus_uconst, 0)
!21 = !DILocation(line: 11, column: 1, scope: !14)
!22 = distinct !DISubprogram(name: "scan", scope: !1, file: !1, line: 4, type: !15, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !17)
!23 = !DILocation(line: 6, column: 17, scope: !22)
!24 = !DILocalVariable(name: "entry", scope: !22, file: !1, line: 6, type: !4)
!25 = distinct !DISubprogram(name: "scan", scope: !1, file: !1, line: 4, type: !15, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !17)
!26 = !DILocation(line: 6, column: 17, scope: !25)
!27 = !DILocalVariable(name: "entry", scope: !25, file: !1, line: 6, type: !4)
!28 = distinct !DISubprogram(name: "scan", scope: !1, file: !1, line: 4, type: !15, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !17)
!29 = !DILocation(line: 6, column: 17, scope: !28)
!30 = !DILocalVariable(name: "entry", scope: !28, file: !1, line: 6, type: !4)
!31 = distinct !DISubprogram(name: "scan", scope: !1, file: !1, line: 4, type: !15, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !17)
!32 = !DILocation(line: 6, column: 17, scope: !31)
!33 = !DILocalVariable(name: "entry", scope: !31, file: !1, line: 6, type: !4)
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