6c207ee5d2
Regarding ``` .option norelax j label .option relax // relaxable instructions // For assembly input, RISCVAsmParser::ParseInstruction will set ForceRelocs (https://reviews.llvm.org/D46423). // For direct object emission, ForceRelocs is not set after https://github.com/llvm/llvm-project/pull/73721 label: ``` The J instruction needs a relocation to ensure the target is correct after linker relaxation. This is related a limitation in the assembler: RISCVAsmBackend::shouldForceRelocation decides upfront whether a relocation is needed, instead of checking more information (whether there are relaxable fragments in between). Despite the limitation, `j label` produces a relocation in direct object emission mode, but was broken by #73721 due to the shouldForceRelocation limitation. Add a workaround to RISCVTargetELFStreamer to emulate the previous behavior. Link: https://github.com/ClangBuiltLinux/linux/issues/1965
32 lines
1.1 KiB
LLVM
32 lines
1.1 KiB
LLVM
;; With +relax, J below needs a relocation to ensure the target is correct
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;; after linker relaxation. See https://github.com/ClangBuiltLinux/linux/issues/1965
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; RUN: llc -mtriple=riscv64 -mattr=-relax -filetype=obj < %s \
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; RUN: | llvm-objdump -d -r - | FileCheck %s
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; RUN: llc -mtriple=riscv64 -mattr=+relax -filetype=obj < %s \
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; RUN: | llvm-objdump -d -r - | FileCheck %s --check-prefixes=CHECK,RELAX
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; CHECK: j {{.*}}
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; RELAX-NEXT: R_RISCV_JAL {{.*}}
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; CHECK-NEXT: auipc ra, 0x0
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; CHECK-NEXT: R_RISCV_CALL_PLT f
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; RELAX-NEXT: R_RISCV_RELAX *ABS*
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; CHECK-NEXT: jalr ra
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define dso_local noundef signext i32 @main() local_unnamed_addr #0 {
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entry:
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callbr void asm sideeffect ".option push\0A.option norvc\0A.option norelax\0Aj $0\0A.option pop\0A", "!i"() #2
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to label %asm.fallthrough [label %label]
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asm.fallthrough: ; preds = %entry
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tail call void @f()
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br label %label
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label: ; preds = %asm.fallthrough, %entry
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ret i32 0
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}
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declare void @f()
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attributes #0 = { nounwind "target-features"="-c,+relax" }
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