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llvm-mirror/test/CodeGen/X86/widen_shuffle-1.ll
Andrea Di Biagio 29af13b774 [DAG] Further improve the logic in DAGCombiner that folds a pair of shuffles into a single shuffle if the resulting mask is legal.
This patch teaches the DAGCombiner how to fold shuffles according to the
following new rules:
  1. shuffle(shuffle(x, y), undef) -> x
  2. shuffle(shuffle(x, y), undef) -> y
  3. shuffle(shuffle(x, y), undef) -> shuffle(x, undef)
  4. shuffle(shuffle(x, y), undef) -> shuffle(y, undef)

The backend avoids to combine shuffles according to rules 3. and 4. if
the resulting shuffle does not have a legal mask. This is to avoid introducing
illegal shuffles that are potentially expanded into a sub-optimal sequence of
target specific dag nodes during vector legalization.

Added test case combine-vec-shuffle-2.ll to verify that we correctly triggers
the new rules when combining shuffles.

llvm-svn: 212748
2014-07-10 18:04:55 +00:00

72 lines
3.1 KiB
LLVM

; RUN: llc < %s -march=x86 -mattr=+sse4.2 | FileCheck %s
; widening shuffle v3float and then a add
define void @shuf(<3 x float>* %dst.addr, <3 x float> %src1,<3 x float> %src2) nounwind {
entry:
; CHECK-LABEL: shuf:
; CHECK: extractps
; CHECK: extractps
%x = shufflevector <3 x float> %src1, <3 x float> %src2, <3 x i32> < i32 0, i32 1, i32 2>
%val = fadd <3 x float> %x, %src2
store <3 x float> %val, <3 x float>* %dst.addr
ret void
; CHECK: ret
}
; widening shuffle v3float with a different mask and then a add
define void @shuf2(<3 x float>* %dst.addr, <3 x float> %src1,<3 x float> %src2) nounwind {
entry:
; CHECK-LABEL: shuf2:
; CHECK: extractps
; CHECK: extractps
%x = shufflevector <3 x float> %src1, <3 x float> %src2, <3 x i32> < i32 0, i32 4, i32 2>
%val = fadd <3 x float> %x, %src2
store <3 x float> %val, <3 x float>* %dst.addr
ret void
; CHECK: ret
}
; Example of when widening a v3float operation causes the DAG to replace a node
; with the operation that we are currently widening, i.e. when replacing
; opA with opB, the DAG will produce new operations with opA.
define void @shuf3(<4 x float> %tmp10, <4 x float> %vecinit15, <4 x float>* %dst) nounwind {
entry:
; CHECK-LABEL: shuf3:
; CHECK-NOT: movlhps
; CHECK-NOT: shufps
; CHECK: pshufd
%shuffle.i.i.i12 = shufflevector <4 x float> %tmp10, <4 x float> %vecinit15, <4 x i32> <i32 0, i32 1, i32 4, i32 5>
%tmp25.i.i = shufflevector <4 x float> %shuffle.i.i.i12, <4 x float> undef, <3 x i32> <i32 0, i32 1, i32 2>
%tmp1.i.i = shufflevector <3 x float> %tmp25.i.i, <3 x float> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
%tmp3.i13 = shufflevector <4 x float> %tmp1.i.i, <4 x float> undef, <3 x i32> <i32 0, i32 1, i32 2> ; <<3 x float>>
%tmp6.i14 = shufflevector <3 x float> %tmp3.i13, <3 x float> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
%tmp97.i = shufflevector <4 x float> %tmp6.i14, <4 x float> undef, <3 x i32> <i32 0, i32 1, i32 2>
%tmp2.i18 = shufflevector <3 x float> %tmp97.i, <3 x float> undef, <4 x i32> <i32 0, i32 1, i32 2, i32 2>
%t5 = bitcast <4 x float> %tmp2.i18 to <4 x i32>
%shr.i.i19 = lshr <4 x i32> %t5, <i32 19, i32 19, i32 19, i32 19>
%and.i.i20 = and <4 x i32> %shr.i.i19, <i32 4080, i32 4080, i32 4080, i32 4080>
%shuffle.i.i.i21 = shufflevector <4 x float> %tmp2.i18, <4 x float> undef, <4 x i32> <i32 2, i32 3, i32 2, i32 3>
store <4 x float> %shuffle.i.i.i21, <4 x float>* %dst
ret void
; CHECK: ret
}
; PR10421: make sure we correctly handle extreme widening with CONCAT_VECTORS
define <8 x i8> @shuf4(<4 x i8> %a, <4 x i8> %b) nounwind readnone {
; CHECK-LABEL: shuf4:
; CHECK-NOT: punpckldq
%vshuf = shufflevector <4 x i8> %a, <4 x i8> %b, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
ret <8 x i8> %vshuf
; CHECK: ret
}
; PR11389: another CONCAT_VECTORS case
define void @shuf5(<8 x i8>* %p) nounwind {
; CHECK-LABEL: shuf5:
%v = shufflevector <2 x i8> <i8 4, i8 33>, <2 x i8> undef, <8 x i32> <i32 1, i32 1, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef>
store <8 x i8> %v, <8 x i8>* %p, align 8
ret void
; CHECK: ret
}