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llvm-mirror/test/CodeGen/RISCV/fixups-diff.ll
Alex Bradbury 94c1bcf630 [RISCV][MC] Don't fold symbol differences if requiresDiffExpressionRelocations is true
When emitting the difference between two symbols, the standard behavior is 
that the difference will be resolved to an absolute value if both of the 
symbols are offsets from the same data fragment. This is undesirable on 
architectures such as RISC-V where relaxation in the linker may cause the 
computed difference to become invalid. This caused an issue when compiling to 
object code, where the size of a function in the debug information was already 
calculated even though it could change as a consequence of relaxation in the 
subsequent linking stage.

This patch inhibits the resolution of symbol differences to absolute values 
where the target's AsmBackend has declared that it does not want these to be 
folded.

Differential Revision: https://reviews.llvm.org/D45773
Patch by Edward Jones.

llvm-svn: 339864
2018-08-16 11:26:37 +00:00

47 lines
1.8 KiB
LLVM

; RUN: llc -filetype=obj -mtriple=riscv32 -mattr=+relax %s -o - \
; RUN: | llvm-readobj -r | FileCheck -check-prefix=RELAX %s
; RUN: llc -filetype=obj -mtriple=riscv32 -mattr=-relax %s -o - \
; RUN: | llvm-readobj -r | FileCheck -check-prefix=NORELAX %s
; Check that a difference between two symbols in the same fragment
; causes relocations to be emitted if and only if relaxation is enabled.
;
; This specific test is checking that the size of the function in
; the debug information is represented by a relocation. This isn't
; an assembly test as the assembler takes a different path through
; LLVM, which is already covered by the fixups-expr.s test.
source_filename = "tmp.c"
target datalayout = "e-m:e-p:32:32-i64:64-n32-S128"
target triple = "riscv32"
define i32 @main() !dbg !7 {
entry:
%retval = alloca i32, align 4
store i32 0, i32* %retval, align 4
ret i32 0
}
; RELAX: 0x22 R_RISCV_ADD32 - 0x0
; RELAX: 0x22 R_RISCV_SUB32 - 0x0
; RELAX: 0x2B R_RISCV_ADD32 - 0x0
; RELAX: 0x2B R_RISCV_SUB32 - 0x0
; NORELAX-NOT: R_RISCV_ADD32
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5}
!llvm.ident = !{!6}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "fixups-diff.ll", directory: "test/MC/RISCV")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{!"clang"}
!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
!8 = !DISubroutineType(types: !9)
!9 = !{!10}
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!11 = !DILocation(line: 2, column: 3, scope: !7)