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[X86] Require 32-byte alignment for 32-byte VMOVNTs.

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We used to accept (and even test, and generate) 16-byte alignment
for 32-byte nontemporal stores, but they require 32-byte alignment,
per SDM. Found by inspection.

Instead of hardcoding 16 in the patfrag, check for natural alignment.
Also fix the autoupgrade and the various tests.

Also, use explicit -mattr instead of -mcpu: I stared at the output
several minutes wondering why I get 2x movntps for the unaligned
case (which is the ideal output, but needs some work: see FIXME),
until I remembered corei7-avx implies +slow-unaligned-mem-32.

llvm-svn: 246733
This commit is contained in:
Ahmed Bougacha 2015-09-02 23:25:39 +00:00
parent 31c92181c8
commit 0c13130c71
5 changed files with 27 additions and 10 deletions
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2
lib/IR/AutoUpgrade.cpp
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@ -370,7 +370,7 @@ void llvm::UpgradeIntrinsicCall(CallInst *CI, Function *NewFn) {
"cast");
StoreInst *SI = Builder.CreateStore(Arg1, BC);
SI->setMetadata(M->getMDKindID("nontemporal"), Node);
SI->setAlignment(16);
SI->setAlignment(32);
// Remove intrinsic.
CI->eraseFromParent();

6
lib/Target/X86/X86InstrFragmentsSIMD.td
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@ -626,12 +626,14 @@ def nontemporalstore : PatFrag<(ops node:$val, node:$ptr),
def alignednontemporalstore : PatFrag<(ops node:$val, node:$ptr),
(nontemporalstore node:$val, node:$ptr), [{
return cast<StoreSDNode>(N)->getAlignment() >= 16;
StoreSDNode *St = cast<StoreSDNode>(N);
return St->getAlignment() >= St->getMemoryVT().getStoreSize();
}]>;
def unalignednontemporalstore : PatFrag<(ops node:$val, node:$ptr),
(nontemporalstore node:$val, node:$ptr), [{
return cast<StoreSDNode>(N)->getAlignment() < 16;
StoreSDNode *St = cast<StoreSDNode>(N);
return St->getAlignment() < St->getMemoryVT().getStoreSize();
}]>;
def mgatherv4i32 : PatFrag<(ops node:$src1, node:$src2, node:$src3),

6
test/CodeGen/X86/avx2-nontemporal.ll
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@ -4,15 +4,15 @@ define void @f(<8 x float> %A, i8* %B, <4 x double> %C, <4 x i64> %E) {
; CHECK: vmovntps %y
%cast = bitcast i8* %B to <8 x float>*
%A2 = fadd <8 x float> %A, <float 0x0, float 0x0, float 0x0, float 0x0, float 0x0, float 0x0, float 0x0, float 0x4200000000000000>
store <8 x float> %A2, <8 x float>* %cast, align 16, !nontemporal !0
store <8 x float> %A2, <8 x float>* %cast, align 32, !nontemporal !0
; CHECK: vmovntdq %y
%cast1 = bitcast i8* %B to <4 x i64>*
%E2 = add <4 x i64> %E, <i64 1, i64 2, i64 3, i64 4>
store <4 x i64> %E2, <4 x i64>* %cast1, align 16, !nontemporal !0
store <4 x i64> %E2, <4 x i64>* %cast1, align 32, !nontemporal !0
; CHECK: vmovntpd %y
%cast2 = bitcast i8* %B to <4 x double>*
%C2 = fadd <4 x double> %C, <double 0x0, double 0x0, double 0x0, double 0x4200000000000000>
store <4 x double> %C2, <4 x double>* %cast2, align 16, !nontemporal !0
store <4 x double> %C2, <4 x double>* %cast2, align 32, !nontemporal !0
ret void
}

2
test/CodeGen/X86/movntdq-no-avx.ll
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@ -5,7 +5,7 @@
define void @test(<2 x i64>* nocapture %a, <2 x i64> %b) nounwind optsize {
entry:
store <2 x i64> %b, <2 x i64>* %a, align 16, !nontemporal !0
store <2 x i64> %b, <2 x i64>* %a, align 32, !nontemporal !0
ret void
}

21
test/CodeGen/X86/nontemporal-2.ll
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@ -1,6 +1,6 @@
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=corei7 | FileCheck %s -check-prefix=CHECK -check-prefix=SSE
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=corei7-avx | FileCheck %s -check-prefix=CHECK -check-prefix=AVX
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=core-avx2 | FileCheck %s -check-prefix=CHECK -check-prefix=AVX2
; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s -check-prefix=CHECK -check-prefix=SSE
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx | FileCheck %s -check-prefix=CHECK -check-prefix=AVX
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx2 | FileCheck %s -check-prefix=CHECK -check-prefix=AVX2
; Make sure that we generate non-temporal stores for the test cases below.
; We use xorps for zeroing, so domain information isn't available anymore.
@ -300,4 +300,19 @@ define void @test_op_v32i8(<32 x i8> %a, <32 x i8> %b, <32 x i8>* %dst) {
ret void
}
; 256-bit NT stores require 256-bit alignment.
; FIXME: For AVX, we could lower this to 2x movntps %xmm. Taken further, we
; could even scalarize to movnti when we have 1-alignment: nontemporal is
; probably always worth even some 20 instruction scalarization.
define void @test_unaligned_v8f32(<8 x float> %a, <8 x float> %b, <8 x float>* %dst) {
; CHECK-LABEL: test_unaligned_v8f32:
; SSE: movntps %xmm
; SSE: movntps %xmm
; AVX-NOT: movnt
; AVX: vmovups %ymm
%r = fadd <8 x float> %a, %b
store <8 x float> %r, <8 x float>* %dst, align 16, !nontemporal !1
ret void
}
!1 = !{i32 1}