7a001a2d92
On PowerPC, FNMSUB (both VSX and non-VSX version) means -(a*b-c). But the backend used to generate these instructions regardless whether nsz flag exists or not. If a*b-c==0, such transformation changes sign of zero. This patch introduces PPC specific FNMSUB ISD opcode, which may help improving combined FMA code sequence. Reviewed By: steven.zhang Differential Revision: https://reviews.llvm.org/D76585
16 lines
534 B
LLVM
16 lines
534 B
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc -verify-machineinstrs < %s -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr8 | FileCheck %s
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define dso_local float @foo(float %0, float %1) local_unnamed_addr {
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; CHECK-LABEL: foo:
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; CHECK: # %bb.0:
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; CHECK-NEXT: xsresp 3, 2
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; CHECK-NEXT: xsmulsp 0, 1, 3
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; CHECK-NEXT: xsnmsubasp 1, 2, 0
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; CHECK-NEXT: xsmaddasp 0, 3, 1
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; CHECK-NEXT: fmr 1, 0
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; CHECK-NEXT: blr
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%3 = fdiv reassoc arcp nsz float %0, %1
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ret float %3
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}
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