e6bf48d110
As of rev ea222be0d, LLVMs assembler will actually try to honour the "fill value" part of p2align directives. X86 printed these as 0x90, which isn't actually what it wanted: we want multi-byte nops for .text padding. Compiling via a textual assembly file produces single-byte nop padding since ea222be0d but the built-in assembler will produce multi-byte nops. This divergent behaviour is undesirable. To fix: don't set the byte padding field for x86, which allows the assembler to pick multi-byte nops. Test that we get the same multi-byte padding when compiled via textual assembly or directly to object file. Added same-align-bytes-with-llasm-llobj.ll to that effect, updated numerous other tests to not contain check-lines for the explicit padding.
47 lines
1.6 KiB
LLVM
47 lines
1.6 KiB
LLVM
; RUN: llc %s -o - -filetype=obj --mcpu=znver2 | llvm-objdump -dr - | FileCheck %s
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; RUN: llc %s -o - -filetype=asm --mcpu=znver2 | llvm-mc - -o - --mcpu=znver2 -filetype=obj -triple x86_64-unknown-linux-gnu | llvm-objdump -dr - | FileCheck %s
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; RUN: llc %s -o - -filetype=asm --mcpu=znver2 | FileCheck %s --check-prefix=ASM
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;; Check that we produce a push, then an align-to-16-bytes p2align.
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;
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; ASM: # %bb.0:
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; ASM-NEXT: pushq %rax
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; ASM-NEXT: .cfi_def_cfa_offset 16
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; ASM-NEXT: .p2align 4{{$}}
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;; When we assemble the file, either using the built-in asssembler or going
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;; via a textual assembly file, we should get the same padding between the
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;; initial push and the next block for alignment. It's a single 15 byte
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;; nop.
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; CHECK: 0: 50
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; CHECK-NEXT: 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax)
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;; Note that we specify a CPU to ensure the same nop patterns are selected
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;; between llvm-mc and llc, just in case defaults changed, which one isn't
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;; important.
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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; Function Attrs: noreturn nounwind uwtable
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define dso_local void @b() local_unnamed_addr {
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entry:
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br label %for.cond
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for.cond:
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tail call void (...) @a()
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br label %for.cond
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}
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declare void @a(...) local_unnamed_addr
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!llvm.module.flags = !{!0, !1, !2, !3}
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!llvm.ident = !{!4}
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!0 = !{i32 1, !"wchar_size", i32 4}
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!1 = !{i32 8, !"PIC Level", i32 2}
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!2 = !{i32 7, !"PIE Level", i32 2}
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!3 = !{i32 7, !"uwtable", i32 2}
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!4 = !{!"clang"}
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