llvm-6502/test/CodeGen/X86/widen_cast-4.ll
Chandler Carruth 98eac0a244 [x86] Re-apply a variant of the x86 side of r212324 now that the rest
has settled without incident, removing the x86-specific and overly
strict 'isVectorSplat' routine in favor of generic and more powerful
splat detection.

The primary motivation and result of this is that the x86 backend can
now see through splats which contain undef elements. This is essential
if we are using a widening form of legalization and I've updated a test
case to also run in that mode as before this change the generated code
for the test case was completely scalarized.

This version of the patch much more carefully handles the undef lanes.
- We aren't overly conservative about them in the shift lowering
  (where we will never use the splat itself).
- One place where the splat would have been re-used by the existing code
  now explicitly constructs a new constant splat that will be safe.
- The broadcast lowering is much more reasonable with undefs by doing
  a correct check of whether the splat is the only user of a loaded
  value, checking that the splat actually crosses multiple lanes before
  using a broadcast, and handling broadcasts of non-constant splats.

As a consequence of the last bullet, the weird usage of vpshufd instead
of vbroadcast is gone, and we actually can lower an AVX splat with
vbroadcastss where before we emitted a really strange pattern of
a vector load and a manual splat across the vector.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212602 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-09 10:06:58 +00:00

79 lines
2.9 KiB
LLVM

; RUN: llc < %s -march=x86 -mattr=+sse4.2 | FileCheck %s
; RUN: llc < %s -march=x86 -mattr=+sse4.2 -x86-experimental-vector-widening-legalization | FileCheck %s --check-prefix=CHECK-WIDE
define void @update(i64* %dst_i, i64* %src_i, i32 %n) nounwind {
; CHECK-LABEL: update:
; CHECK-WIDE-LABEL: update:
entry:
%dst_i.addr = alloca i64* ; <i64**> [#uses=2]
%src_i.addr = alloca i64* ; <i64**> [#uses=2]
%n.addr = alloca i32 ; <i32*> [#uses=2]
%i = alloca i32, align 4 ; <i32*> [#uses=8]
%dst = alloca <8 x i8>*, align 4 ; <<8 x i8>**> [#uses=2]
%src = alloca <8 x i8>*, align 4 ; <<8 x i8>**> [#uses=2]
store i64* %dst_i, i64** %dst_i.addr
store i64* %src_i, i64** %src_i.addr
store i32 %n, i32* %n.addr
store i32 0, i32* %i
br label %forcond
forcond: ; preds = %forinc, %entry
%tmp = load i32* %i ; <i32> [#uses=1]
%tmp1 = load i32* %n.addr ; <i32> [#uses=1]
%cmp = icmp slt i32 %tmp, %tmp1 ; <i1> [#uses=1]
br i1 %cmp, label %forbody, label %afterfor
forbody: ; preds = %forcond
%tmp2 = load i32* %i ; <i32> [#uses=1]
%tmp3 = load i64** %dst_i.addr ; <i64*> [#uses=1]
%arrayidx = getelementptr i64* %tmp3, i32 %tmp2 ; <i64*> [#uses=1]
%conv = bitcast i64* %arrayidx to <8 x i8>* ; <<8 x i8>*> [#uses=1]
store <8 x i8>* %conv, <8 x i8>** %dst
%tmp4 = load i32* %i ; <i32> [#uses=1]
%tmp5 = load i64** %src_i.addr ; <i64*> [#uses=1]
%arrayidx6 = getelementptr i64* %tmp5, i32 %tmp4 ; <i64*> [#uses=1]
%conv7 = bitcast i64* %arrayidx6 to <8 x i8>* ; <<8 x i8>*> [#uses=1]
store <8 x i8>* %conv7, <8 x i8>** %src
%tmp8 = load i32* %i ; <i32> [#uses=1]
%tmp9 = load <8 x i8>** %dst ; <<8 x i8>*> [#uses=1]
%arrayidx10 = getelementptr <8 x i8>* %tmp9, i32 %tmp8 ; <<8 x i8>*> [#uses=1]
%tmp11 = load i32* %i ; <i32> [#uses=1]
%tmp12 = load <8 x i8>** %src ; <<8 x i8>*> [#uses=1]
%arrayidx13 = getelementptr <8 x i8>* %tmp12, i32 %tmp11 ; <<8 x i8>*> [#uses=1]
%tmp14 = load <8 x i8>* %arrayidx13 ; <<8 x i8>> [#uses=1]
%add = add <8 x i8> %tmp14, < i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1 > ; <<8 x i8>> [#uses=1]
%shr = ashr <8 x i8> %add, < i8 2, i8 2, i8 2, i8 2, i8 2, i8 2, i8 2, i8 2 > ; <<8 x i8>> [#uses=1]
store <8 x i8> %shr, <8 x i8>* %arrayidx10
br label %forinc
; CHECK: %forbody
; CHECK: pmovzxbw
; CHECK-NEXT: paddw
; CHECK-NEXT: psllw $8
; CHECK-NEXT: psraw $8
; CHECK-NEXT: psraw $2
; CHECK-NEXT: pshufb
; CHECK-NEXT: movlpd
;
; FIXME: We shouldn't require both a movd and an insert.
; CHECK-WIDE: %forbody
; CHECK-WIDE: movd
; CHECK-WIDE-NEXT: pinsrd
; CHECK-WIDE-NEXT: paddb
; CHECK-WIDE-NEXT: psrlw $2
; CHECK-WIDE-NEXT: pand
; CHECK-WIDE-NEXT: pxor
; CHECK-WIDE-NEXT: psubb
; CHECK-WIDE-NEXT: pextrd
; CHECK-WIDE-NEXT: movd
forinc: ; preds = %forbody
%tmp15 = load i32* %i ; <i32> [#uses=1]
%inc = add i32 %tmp15, 1 ; <i32> [#uses=1]
store i32 %inc, i32* %i
br label %forcond
afterfor: ; preds = %forcond
ret void
}