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llvm-project/llvm/test/CodeGen/ARM/constantpool-promote-dbg.ll

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[ARM] Temporarily disable globals promotion to constant pools to prevent miscompilation Summary: A temporary workaround for PR32780 - rematerialized instructions accessing the same promoted global through different constant pool entries. The patch turns off the globals promotion optimization leaving all its code in place, so that it can be easily turned on once PR32780 is fixed. Since this is a miscompilation issue causing generation of misbehaving code, and the problem is very subtle, the patch might be valuable enough to get into 4.0.1. Reviewers: efriedma, jmolloy Reviewed By: efriedma Subscribers: aemerson, javed.absar, llvm-commits, rengolin, asl, tstellar Differential Revision: https://reviews.llvm.org/D33446 llvm-svn: 303679
2017-05-24 03:38:37 +08:00
; RUN: llc -relocation-model=static -arm-promote-constant < %s | FileCheck %s
[ARM] Promote small global constants to constant pools If a constant is unamed_addr and is only used within one function, we can save on the code size and runtime cost of an indirection by changing the global's storage to inside the constant pool. For example, instead of: ldr r0, .CPI0 bl printf bx lr .CPI0: &format_string format_string: .asciz "hello, world!\n" We can emit: adr r0, .CPI0 bl printf bx lr .CPI0: .asciz "hello, world!\n" This can cause significant code size savings when many small strings are used in one function (4 bytes per string). This recommit contains fixes for a nasty bug related to fast-isel fallback - because fast-isel doesn't know about this optimization, if it runs and emits references to a string that we inline (because fast-isel fell back to SDAG) we will end up with an inlined string and also an out-of-line string, and we won't emit the out-of-line string, causing backend failures. It also contains fixes for emitting .text relocations which made the sanitizer bots unhappy. llvm-svn: 282387
2016-09-26 15:26:24 +08:00
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv7m--linux-gnu"
@.str = private unnamed_addr constant [4 x i8] c"abc\00", align 1
; CHECK-LABEL: fn1
; CHECK: .str:
define arm_aapcscc i8* @fn1() local_unnamed_addr #0 !dbg !8 {
entry:
ret i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i32 0, i32 0), !dbg !14
}
; CHECK-LABEL: fn2
; CHECK-NOT: .str:
define arm_aapcscc i8* @fn2() local_unnamed_addr #0 !dbg !15 {
entry:
ret i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i32 0, i32 1), !dbg !16
}
attributes #0 = { minsize norecurse nounwind optsize readnone "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="cortex-m3" "target-features"="+hwdiv,+soft-float,-crypto,-neon" "unsafe-fp-math"="false" "use-soft-float"="true" }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5, !6}
!llvm.ident = !{!7}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0 (http://llvm.org/git/clang.git 075a2bc2570dfcbb6d6aed6c836e4c62b37afea6)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "/Users/jammol01/Code/test.c", directory: "/Users/jammol01/Code/llvm-git/build")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{i32 1, !"min_enum_size", i32 4}
!7 = !{!"clang version 3.9.0 (http://llvm.org/git/clang.git 075a2bc2570dfcbb6d6aed6c836e4c62b37afea6)"}
!8 = distinct !DISubprogram(name: "fn1", scope: !1, file: !1, line: 1, type: !9, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: true, unit: !0, variables: !2)
!9 = !DISubroutineType(types: !10)
!10 = !{!11}
!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 32, align: 32)
!12 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !13)
!13 = !DIBasicType(name: "char", size: 8, align: 8, encoding: DW_ATE_unsigned_char)
!14 = !DILocation(line: 2, column: 5, scope: !8)
!15 = distinct !DISubprogram(name: "fn2", scope: !1, file: !1, line: 4, type: !9, isLocal: false, isDefinition: true, scopeLine: 4, isOptimized: true, unit: !0, variables: !2)
!16 = !DILocation(line: 5, column: 5, scope: !15)