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According to IR LangRef, the FMF flag: contract Allow floating-point contraction (e.g. fusing a multiply followed by an addition into a fused multiply-and-add). reassoc Allow reassociation transformations for floating-point instructions. This may dramatically change results in floating-point. My understanding is that these two flags shouldn't imply each other, as we might have a SDNode that can be reassociated with others, but not contractble. eg: We may want following fmul/fad/fsub to freely reassoc, but don't want fma being generated here. %F = fmul reassoc double %A, %B ; <double> [#uses=1] %G = fmul reassoc double %C, %D ; <double> [#uses=1] %H = fadd reassoc double %F, %G ; <double> [#uses=1] %I = fsub reassoc double %H, %E ; <double> [#uses=1] Before https://reviews.llvm.org/D45710, `reassoc` flag actually did not imply isContratable either. The current implementation also only check the flag in fadd node, ignoring fmul node, this patch update that as well. Reviewed By: spatel, qiucf Differential Revision: https://reviews.llvm.org/D104247
26 lines
903 B
LLVM
26 lines
903 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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; RUN: llc -verify-machineinstrs < %s -mtriple=powerpc64-ibm-aix-xcoff -mcpu=pwr8 -vec-extabi | FileCheck %s
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define dso_local float @foo_nosw(float %0, float %1) local_unnamed_addr {
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; CHECK-LABEL: foo_nosw:
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; CHECK: # %bb.0:
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; CHECK-NEXT: xsdivsp 1, 1, 2
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; CHECK-NEXT: blr
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%3 = fdiv contract reassoc arcp nsz float %0, %1
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ret float %3
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}
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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 contract reassoc arcp nsz ninf float %0, %1
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ret float %3
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}
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