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a4fc069a94
This decreases use count of Op1, potentially allows us to further hoist said 'neg' later on, and results in marginally better X86 codegen. Name: (Op1 & С) - Op1 -> -(Op1 & ~C) %o = and i64 %Op1, C1 %r = sub i64 %o, %Op1 => %n = and i64 %Op1, ~C1 %r = sub i64 0, %n https://rise4fun.com/Alive/rwgA https://godbolt.org/z/R_RMfM https://bugs.llvm.org/show_bug.cgi?id=44427
99 lines
2.7 KiB
LLVM
99 lines
2.7 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -S < %s -instcombine | FileCheck %s
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; Fold
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; (X & C) - X
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; to
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; - (X & ~C)
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;
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; This allows us to possibly hoist said negation further out,
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; and decreases use count of X.
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; https://bugs.llvm.org/show_bug.cgi?id=44427
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; Base tests
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define i8 @t0(i8 %x) {
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; CHECK-LABEL: @t0(
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; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X:%.*]], -43
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; CHECK-NEXT: [[NEGBIAS:%.*]] = sub i8 0, [[TMP1]]
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; CHECK-NEXT: ret i8 [[NEGBIAS]]
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;
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%unbiasedx = and i8 %x, 42
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%negbias = sub i8 %unbiasedx, %x
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ret i8 %negbias
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}
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define <2 x i8> @t1_vec(<2 x i8> %x) {
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; CHECK-LABEL: @t1_vec(
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; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i8> [[X:%.*]], <i8 -43, i8 -43>
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; CHECK-NEXT: [[NEGBIAS:%.*]] = sub <2 x i8> zeroinitializer, [[TMP1]]
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; CHECK-NEXT: ret <2 x i8> [[NEGBIAS]]
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;
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%unbiasedx = and <2 x i8> %x, <i8 42, i8 42>
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%negbias = sub <2 x i8> %unbiasedx, %x
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ret <2 x i8> %negbias
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}
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define <2 x i8> @t2_vec_undef(<2 x i8> %x) {
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; CHECK-LABEL: @t2_vec_undef(
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; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i8> [[X:%.*]], <i8 -43, i8 undef>
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; CHECK-NEXT: [[NEGBIAS:%.*]] = sub <2 x i8> zeroinitializer, [[TMP1]]
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; CHECK-NEXT: ret <2 x i8> [[NEGBIAS]]
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;
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%unbiasedx = and <2 x i8> %x, <i8 42, i8 undef>
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%negbias = sub <2 x i8> %unbiasedx, %x
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ret <2 x i8> %negbias
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}
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define <2 x i8> @t3_vec_nonsplat(<2 x i8> %x) {
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; CHECK-LABEL: @t3_vec_nonsplat(
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; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i8> [[X:%.*]], <i8 -43, i8 -45>
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; CHECK-NEXT: [[NEGBIAS:%.*]] = sub <2 x i8> zeroinitializer, [[TMP1]]
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; CHECK-NEXT: ret <2 x i8> [[NEGBIAS]]
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;
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%unbiasedx = and <2 x i8> %x, <i8 42, i8 44>
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%negbias = sub <2 x i8> %unbiasedx, %x
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ret <2 x i8> %negbias
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}
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; Extra uses always prevent fold
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declare void @use8(i8)
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define i8 @n4_extrause(i8 %x) {
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; CHECK-LABEL: @n4_extrause(
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; CHECK-NEXT: [[UNBIASEDX:%.*]] = and i8 [[X:%.*]], 42
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; CHECK-NEXT: call void @use8(i8 [[UNBIASEDX]])
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; CHECK-NEXT: [[NEGBIAS:%.*]] = sub i8 [[UNBIASEDX]], [[X]]
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; CHECK-NEXT: ret i8 [[NEGBIAS]]
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;
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%unbiasedx = and i8 %x, 42
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call void @use8(i8 %unbiasedx)
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%negbias = sub i8 %unbiasedx, %x
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ret i8 %negbias
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}
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; Negative tests
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define i8 @n5(i8 %x) {
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; CHECK-LABEL: @n5(
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; CHECK-NEXT: [[NEGBIAS:%.*]] = and i8 [[X:%.*]], -43
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; CHECK-NEXT: ret i8 [[NEGBIAS]]
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;
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%unbiasedx = and i8 %x, 42
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%negbias = sub i8 %x, %unbiasedx ; wrong order
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ret i8 %negbias
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}
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define i8 @n6(i8 %x0, i8 %x1) {
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; CHECK-LABEL: @n6(
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; CHECK-NEXT: [[UNBIASEDX:%.*]] = and i8 [[X1:%.*]], 42
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; CHECK-NEXT: [[NEGBIAS:%.*]] = sub i8 [[UNBIASEDX]], [[X0:%.*]]
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; CHECK-NEXT: ret i8 [[NEGBIAS]]
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;
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%unbiasedx = and i8 %x1, 42 ; not %x0
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%negbias = sub i8 %unbiasedx, %x0 ; not %x1
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ret i8 %negbias
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}
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