[llvm] r342347 - [x86] fix uses check in broadcast transform (PR38949)
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Sun Sep 16 08:41:56 PDT 2018
Author: spatel
Date: Sun Sep 16 08:41:56 2018
New Revision: 342347
URL: http://llvm.org/viewvc/llvm-project?rev=342347&view=rev
Log:
[x86] fix uses check in broadcast transform (PR38949)
https://bugs.llvm.org/show_bug.cgi?id=38949
It's not clear to me that we even need a one-use check in this fold.
Ie, 2 independent loads might be better than a load+dependent shuffle.
Note that the existing re-use tests are not affected. We actually do form a
broadcast node in those tests now because there's no extra use of the
insert_subvector node in those cases. But something later in isel pattern
matching decides that it is not worth using a broadcast for the full load in
those tests:
Legalized selection DAG: %bb.0 'test_broadcast_2f64_4f64_reuse:'
t7: v2f64,ch = load<(load 16 from %ir.p0)> t0, t2, undef:i64
t4: i64,ch = CopyFromReg t0, Register:i64 %1
t10: ch = store<(store 16 into %ir.p1)> t7:1, t7, t4, undef:i64
t18: v4f64 = insert_subvector undef:v4f64, t7, Constant:i64<0>
t20: v4f64 = insert_subvector t18, t7, Constant:i64<2>
Becomes:
t7: v2f64,ch = load<(load 16 from %ir.p0)> t0, t2, undef:i64
t4: i64,ch = CopyFromReg t0, Register:i64 %1
t10: ch = store<(store 16 into %ir.p1)> t7:1, t7, t4, undef:i64
t21: v4f64 = X86ISD::SUBV_BROADCAST t7
ISEL: Starting selection on root node: t21: v4f64 = X86ISD::SUBV_BROADCAST t7
...
Created node: t27: v4f64 = INSERT_SUBREG IMPLICIT_DEF:v4f64, t7, TargetConstant:i32<7>
Morphed node: t21: v4f64 = VINSERTF128rr t27, t7, TargetConstant:i8<1>
Modified:
llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
llvm/trunk/test/CodeGen/X86/avx-vbroadcastf128.ll
Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=342347&r1=342346&r2=342347&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Sun Sep 16 08:41:56 2018
@@ -40114,11 +40114,10 @@ static SDValue combineInsertSubvector(SD
return Ld;
}
}
- // If lower/upper loads are the same and the only users of the load, then
- // lower to a VBROADCASTF128/VBROADCASTI128/etc.
+ // If lower/upper loads are the same and there's no other use of the lower
+ // load, then splat the loaded value with a broadcast.
if (auto *Ld = dyn_cast<LoadSDNode>(peekThroughOneUseBitcasts(SubVec2)))
- if (SubVec2 == SubVec && ISD::isNormalLoad(Ld) &&
- SDNode::areOnlyUsersOf({N, Vec.getNode()}, SubVec2.getNode()))
+ if (SubVec2 == SubVec && ISD::isNormalLoad(Ld) && Vec.hasOneUse())
return DAG.getNode(X86ISD::SUBV_BROADCAST, dl, OpVT, SubVec);
// If this is subv_broadcast insert into both halves, use a larger
Modified: llvm/trunk/test/CodeGen/X86/avx-vbroadcastf128.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/avx-vbroadcastf128.ll?rev=342347&r1=342346&r2=342347&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/avx-vbroadcastf128.ll (original)
+++ llvm/trunk/test/CodeGen/X86/avx-vbroadcastf128.ll Sun Sep 16 08:41:56 2018
@@ -106,16 +106,14 @@ define void @subv_reuse_is_ok(<4 x float
; X32: # %bb.0:
; X32-NEXT: movl {{[0-9]+}}(%esp), %eax
; X32-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; X32-NEXT: vmovups (%ecx), %xmm0
-; X32-NEXT: vinsertf128 $1, %xmm0, %ymm0, %ymm0
+; X32-NEXT: vbroadcastf128 {{.*#+}} ymm0 = mem[0,1,0,1]
; X32-NEXT: vmovups %ymm0, (%eax)
; X32-NEXT: vzeroupper
; X32-NEXT: retl
;
; X64-LABEL: subv_reuse_is_ok:
; X64: # %bb.0:
-; X64-NEXT: vmovups (%rdi), %xmm0
-; X64-NEXT: vinsertf128 $1, %xmm0, %ymm0, %ymm0
+; X64-NEXT: vbroadcastf128 {{.*#+}} ymm0 = mem[0,1,0,1]
; X64-NEXT: vmovups %ymm0, (%rsi)
; X64-NEXT: vzeroupper
; X64-NEXT: retq
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