llvm-6502/test/CodeGen/X86/vselect-avx.ll
Quentin Colombet d465eced34 [X86] Lower VSELECT into SHRUNKBLEND when we shrink the bits used into the
condition to match a blend.
This prevents optimizations that work on VSELECT to perform invalid
transformations. Indeed, the optimized condition does not match the vector
boolean content that is expected and bad things may happen.

This patch yields the exact same code on the whole test-suite + specs (-O3 and
-O3 -march=core-avx2), it improves one test case (vector-blend.ll) and fixes a
bug reduced in vselect-avx.ll.

<rdar://problem/18819506>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221429 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-06 02:25:03 +00:00

86 lines
3.8 KiB
LLVM

; RUN: llc %s -o - -mattr=+avx | FileCheck %s
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx"
; For this test we used to optimize the <i1 true, i1 false, i1 false, i1 true>
; mask into <i32 2147483648, i32 0, i32 0, i32 2147483648> because we thought
; we would lower that into a blend where only the high bit is relevant.
; However, since the whole mask is constant, this is simplified incorrectly
; by the generic code, because it was expecting -1 in place of 2147483648.
;
; The problem does not occur without AVX, because vselect of v4i32 is not legal
; nor custom.
;
; <rdar://problem/18675020>
; CHECK-LABEL: test:
; CHECK: vmovdqa {{.*#+}} xmm0 = [65535,0,0,65535]
; CHECK: vmovdqa {{.*#+}} xmm2 = [65533,124,125,14807]
; CHECK: ret
define void @test(<4 x i16>* %a, <4 x i16>* %b) {
body:
%predphi = select <4 x i1> <i1 true, i1 false, i1 false, i1 true>, <4 x i16> <i16 -3, i16 545, i16 4385, i16 14807>, <4 x i16> <i16 123, i16 124, i16 125, i16 127>
%predphi42 = select <4 x i1> <i1 true, i1 false, i1 false, i1 true>, <4 x i16> <i16 -1, i16 -1, i16 -1, i16 -1>, <4 x i16> zeroinitializer
store <4 x i16> %predphi, <4 x i16>* %a, align 8
store <4 x i16> %predphi42, <4 x i16>* %b, align 8
ret void
}
; Improve code coverage.
;
; When shrinking the condition used into the select to match a blend, this
; test case exercises the path where the modified node is not the root
; of the condition.
;
; CHECK-LABEL: test2:
; CHECK: vpslld $31, %xmm0, %xmm0
; CHECK-NEXT: vpmovsxdq %xmm0, %xmm1
; CHECK-NEXT: vpshufd $78, %xmm0, %xmm0 ## xmm0 = xmm0[2,3,0,1]
; CHECK-NEXT: vpmovsxdq %xmm0, %xmm0
; CHECK-NEXT: vinsertf128 $1, %xmm0, %ymm1, [[MASK:%ymm[0-9]+]]
; CHECK: vblendvpd [[MASK]]
; CHECK: retq
define void @test2(double** %call1559, i64 %indvars.iv4198, <4 x i1> %tmp1895) {
bb:
%arrayidx1928 = getelementptr inbounds double** %call1559, i64 %indvars.iv4198
%tmp1888 = load double** %arrayidx1928, align 8
%predphi.v.v = select <4 x i1> %tmp1895, <4 x double> <double -5.000000e-01, double -5.000000e-01, double -5.000000e-01, double -5.000000e-01>, <4 x double> <double 5.000000e-01, double 5.000000e-01, double 5.000000e-01, double 5.000000e-01>
%tmp1900 = bitcast double* %tmp1888 to <4 x double>*
store <4 x double> %predphi.v.v, <4 x double>* %tmp1900, align 8
ret void
}
; For this test, we used to optimized the conditional mask for the blend, i.e.,
; we shrunk some of its bits.
; However, this same mask was used in another select (%predphi31) that turned out
; to be optimized into a and. In that case, the conditional mask was wrong.
;
; Make sure that the and is fed by the original mask.
;
; <rdar://problem/18819506>
; Note: For now, hard code ORIG_MASK and SHRUNK_MASK registers, because we
; cannot express that ORIG_MASK must not be equal to ORIG_MASK. Otherwise,
; even a faulty pattern would pass!
;
; CHECK-LABEL: test3:
; Compute the original mask.
; CHECK: vpcmpeqd {{%xmm[0-9]+}}, {{%xmm[0-9]+}}, [[ORIG_MASK:%xmm0]]
; Shrink the bit of the mask.
; CHECK-NEXT: vpslld $31, [[ORIG_MASK]], [[SHRUNK_MASK:%xmm3]]
; Use the shrunk mask in the blend.
; CHECK-NEXT: vblendvps [[SHRUNK_MASK]], %xmm{{[0-9]+}}, %xmm{{[0-9]+}}, %xmm{{[0-9]+}}
; Use the original mask in the and.
; CHECK-NEXT: vpand LCPI2_2(%rip), [[ORIG_MASK]], {{%xmm[0-9]+}}
; CHECK: retq
define void @test3(<4 x i32> %induction30, <4 x i16>* %tmp16, <4 x i16>* %tmp17, <4 x i16> %tmp3, <4 x i16> %tmp12) {
%tmp6 = srem <4 x i32> %induction30, <i32 3, i32 3, i32 3, i32 3>
%tmp7 = icmp eq <4 x i32> %tmp6, zeroinitializer
%predphi = select <4 x i1> %tmp7, <4 x i16> %tmp3, <4 x i16> %tmp12
%predphi31 = select <4 x i1> %tmp7, <4 x i16> <i16 -1, i16 -1, i16 -1, i16 -1>, <4 x i16> zeroinitializer
store <4 x i16> %predphi31, <4 x i16>* %tmp16, align 8
store <4 x i16> %predphi, <4 x i16>* %tmp17, align 8
ret void
}