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llvm-mirror/test/CodeGen/ARM/2012-03-13-DAGCombineBug.ll
Chad Rosier a588421976 When performing a truncating store, it's possible to rearrange the data
in-register, such that we can use a single vector store rather then a 
series of scalar stores.

For func_4_8 the generated code

	vldr	d16, LCPI0_0
	vmov	d17, r0, r1
	vadd.i16	d16, d17, d16
	vmov.u16	r0, d16[3]
	strb	r0, [r2, #3]
	vmov.u16	r0, d16[2]
	strb	r0, [r2, #2]
	vmov.u16	r0, d16[1]
	strb	r0, [r2, #1]
	vmov.u16	r0, d16[0]
	strb	r0, [r2]
	bx	lr

becomes

	vldr	d16, LCPI0_0
	vmov	d17, r0, r1
	vadd.i16	d16, d17, d16
	vuzp.8	d16, d17
	vst1.32	{d16[0]}, [r2, :32]
	bx	lr

I'm not fond of how this combine pessimizes 2012-03-13-DAGCombineBug.ll,
but I couldn't think of a way to judiciously apply this combine.

This

	ldrh	r0, [r0, #4]
	strh	r0, [r1]

becomes

	vldr	d16, [r0]
	vmov.u16	r0, d16[2]
	vmov.32	d16[0], r0
	vuzp.16	d16, d17
	vst1.32	{d16[0]}, [r1, :32]

PR11158
rdar://10703339

llvm-svn: 154340
2012-04-09 20:32:02 +00:00

16 lines
570 B
LLVM

; RUN: llc < %s -mtriple=thumbv7-apple-ios | FileCheck %s
; rdar://11035895
; DAG combine incorrectly optimize (i32 vextract (v4i16 load $addr), c) to
; (i16 load $addr+c*sizeof(i16)). It should have issued an extload instead. i.e.
; (i32 extload $addr+c*sizeof(i16)
define void @test_hi_short3(<3 x i16> * nocapture %srcA, <2 x i16> * nocapture %dst) nounwind {
entry:
; CHECK: vst1.32
%0 = load <3 x i16> * %srcA, align 8
%1 = shufflevector <3 x i16> %0, <3 x i16> undef, <2 x i32> <i32 2, i32 undef>
store <2 x i16> %1, <2 x i16> * %dst, align 4
ret void
}