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llvm-project/llvm/test/Transforms/MemCpyOpt/nontemporal.ll

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[MemCpyOpt] Fix wrong merging adjacent nontemporal stores into memset calls. Pass MemCpyOpt doesn't check if a store instruction is nontemporal. As a consequence, adjacent nontemporal stores are always merged into a memset call. Example: ;;; define void @foo(<4 x float>* nocapture %p) { entry: store <4 x float> zeroinitializer, <4 x float>* %p, align 16, !nontemporal !0 %p1 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 1 store <4 x float> zeroinitializer, <4 x float>* %p1, align 16, !nontemporal !0 ret void } !0 = !{i32 1} ;;; In this example, the two nontemporal stores are combined to a memset of zero which does not preserve the nontemporal hint. Later on the backend (tested on a x86-64 corei7) expands that memset call into a sequence of two normal 16-byte aligned vector stores. opt -memcpyopt example.ll -S -o - | llc -mcpu=corei7 -o - Before: xorps %xmm0, %xmm0 movaps %xmm0, 16(%rdi) movaps %xmm0, (%rdi) With this patch, we no longer merge nontemporal stores into calls to memset. In this example, llc correctly expands the two stores into two movntps: xorps %xmm0, %xmm0 movntps %xmm0, 16(%rdi) movntps %xmm0, (%rdi) In theory, we could extend the usage of !nontemporal metadata to memcpy/memset calls. However a change like that would only have the effect of forcing the backend to expand !nontemporal memsets back to sequences of store instructions. A memset library call would not have exactly the same semantic of a builtin !nontemporal memset call. So, SelectionDAG will have to conservatively expand it back to a sequence of !nontemporal stores (effectively undoing the merging). Differential Revision: http://reviews.llvm.org/D13519 llvm-svn: 249820
2015-10-09 18:53:41 +08:00
; RUN: opt < %s -memcpyopt -S | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
; Verify that we don't combine nontemporal stores into memset calls.
define void @nontemporal_stores_1(<4 x float>* nocapture %dst) {
; CHECK-LABEL: @nontemporal_stores_1
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %dst, align 16, !nontemporal !0
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr1, align 16, !nontemporal !0
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr2, align 16, !nontemporal !0
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr3, align 16, !nontemporal !0
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr4, align 16, !nontemporal !0
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr5, align 16, !nontemporal !0
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr6, align 16, !nontemporal !0
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr7, align 16, !nontemporal !0
; CHECK-NEXT: ret void
entry:
store <4 x float> zeroinitializer, <4 x float>* %dst, align 16, !nontemporal !0
%ptr1 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 1
store <4 x float> zeroinitializer, <4 x float>* %ptr1, align 16, !nontemporal !0
%ptr2 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 2
store <4 x float> zeroinitializer, <4 x float>* %ptr2, align 16, !nontemporal !0
%ptr3 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 3
store <4 x float> zeroinitializer, <4 x float>* %ptr3, align 16, !nontemporal !0
%ptr4 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 4
store <4 x float> zeroinitializer, <4 x float>* %ptr4, align 16, !nontemporal !0
%ptr5 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 5
store <4 x float> zeroinitializer, <4 x float>* %ptr5, align 16, !nontemporal !0
%ptr6 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 6
store <4 x float> zeroinitializer, <4 x float>* %ptr6, align 16, !nontemporal !0
%ptr7 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 7
store <4 x float> zeroinitializer, <4 x float>* %ptr7, align 16, !nontemporal !0
ret void
}
define void @nontemporal_stores_2(<4 x float>* nocapture %dst) {
; CHECK-LABEL: @nontemporal_stores_2
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %dst, align 16, !nontemporal !0
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %ptr1, align 16, !nontemporal !0
; CHECK-NEXT: ret void
entry:
store <4 x float> zeroinitializer, <4 x float>* %dst, align 16, !nontemporal !0
%ptr1 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 1
store <4 x float> zeroinitializer, <4 x float>* %ptr1, align 16, !nontemporal !0
ret void
}
!0 = !{i32 1}