[llvm] r338599 - [X86] FastISel fall back on !absolute_symbol GVs

[Hans Wennborg via llvm-commits]

Merged to 7.0 in r338847.

On Wed, Aug 1, 2018 at 7:44 PM, Vlad Tsyrklevich via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: vlad.tsyrklevich
> Date: Wed Aug  1 10:44:37 2018
> New Revision: 338599
>
> URL: http://llvm.org/viewvc/llvm-project?rev=338599&view=rev
> Log:
> [X86] FastISel fall back on !absolute_symbol GVs
>
> Summary:
> D25878, which added support for !absolute_symbol for normal X86 ISel,
> did not add support for materializing references to absolute symbols for
> X86 FastISel. This causes build failures because FastISel generates
> PC-relative relocations for absolute symbols. Fall back to normal ISel
> for references to !absolute_symbol GVs. Fix for PR38200.
>
> Reviewers: pcc, craig.topper
>
> Reviewed By: pcc
>
> Subscribers: hiraditya, llvm-commits, kcc
>
> Differential Revision: https://reviews.llvm.org/D50116
>
> Added:
>     llvm/trunk/test/CodeGen/X86/absolute-bit-mask-fastisel.ll
> Modified:
>     llvm/trunk/lib/Target/X86/X86FastISel.cpp
>
> Modified: llvm/trunk/lib/Target/X86/X86FastISel.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FastISel.cpp?rev=338599&r1=338598&r2=338599&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/X86FastISel.cpp (original)
> +++ llvm/trunk/lib/Target/X86/X86FastISel.cpp Wed Aug  1 10:44:37 2018
> @@ -738,6 +738,10 @@ bool X86FastISel::handleConstantAddresse
>      if (GV->isThreadLocal())
>        return false;
>
> +    // Can't handle !absolute_symbol references yet.
> +    if (GV->isAbsoluteSymbolRef())
> +      return false;
> +
>      // RIP-relative addresses can't have additional register operands, so if
>      // we've already folded stuff into the addressing mode, just force the
>      // global value into its own register, which we can use as the basereg.
>
> Added: llvm/trunk/test/CodeGen/X86/absolute-bit-mask-fastisel.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/absolute-bit-mask-fastisel.ll?rev=338599&view=auto
> ==============================================================================
> --- llvm/trunk/test/CodeGen/X86/absolute-bit-mask-fastisel.ll (added)
> +++ llvm/trunk/test/CodeGen/X86/absolute-bit-mask-fastisel.ll Wed Aug  1 10:44:37 2018
> @@ -0,0 +1,28 @@
> +; RUN: llc < %s | FileCheck %s
> +; RUN: llc -relocation-model=pic < %s | FileCheck %s
> +
> +; Regression test for PR38200
> +
> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at bit_mask8 = external hidden global i8, !absolute_symbol !0
> +
> +declare void @f()
> +
> +define void @foo8(i8* %ptr) noinline optnone {
> +  %load = load i8, i8* %ptr
> +  ; CHECK: movl $bit_mask8, %ecx
> +  %and = and i8 %load, ptrtoint (i8* @bit_mask8 to i8)
> +  %icmp = icmp eq i8 %and, 0
> +  br i1 %icmp, label %t, label %f
> +
> +t:
> +  call void @f()
> +  ret void
> +
> +f:
> +  ret void
> +}
> +
> +!0 = !{i64 0, i64 256}
>
>
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