[llvm] r356293 - [SimplifyDemandedVec] Strengthen handling all undef lanes (particularly GEPs)
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 15 12:54:06 PDT 2019
Author: reames
Date: Fri Mar 15 12:54:06 2019
New Revision: 356293
URL: http://llvm.org/viewvc/llvm-project?rev=356293&view=rev
Log:
[SimplifyDemandedVec] Strengthen handling all undef lanes (particularly GEPs)
A change of two parts:
1) A generic enhancement for all callers of SDVE to exploit the fact that if all lanes are undef, the result is undef.
2) A GEP specific piece to strengthen/fix the vector index undef element handling, and call into the generic infrastructure when visiting the GEP.
The result is that we replace a vector gep with at least one undef in each lane with a undef. We can also do the same for vector intrinsics. Once the masked.load patch (D57372) has landed, I'll update to include call tests as well.
Differential Revision: https://reviews.llvm.org/D57468
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=356293&r1=356292&r2=356293&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Fri Mar 15 12:54:06 2019
@@ -1908,8 +1908,7 @@ Instruction *InstCombiner::visitCallInst
if (Changed) return II;
}
- // For vector result intrinsics, use the generic demanded vector support to
- // simplify any operands before moving on to the per-intrinsic rules.
+ // For vector result intrinsics, use the generic demanded vector support.
if (II->getType()->isVectorTy()) {
auto VWidth = II->getType()->getVectorNumElements();
APInt UndefElts(VWidth, 0);
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp?rev=356293&r1=356292&r2=356293&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp Fri Mar 15 12:54:06 2019
@@ -1175,9 +1175,18 @@ Value *InstCombiner::SimplifyDemandedVec
// wouldn't have a vector result to get here. Note that we intentionally
// merge the undef bits here since gepping with either an undef base or
// index results in undef.
- for (unsigned i = 0; i < I->getNumOperands(); i++)
- if (I->getOperand(i)->getType()->isVectorTy())
- simplifyAndSetOp(I, i, DemandedElts, UndefElts);
+ for (unsigned i = 0; i < I->getNumOperands(); i++) {
+ if (isa<UndefValue>(I->getOperand(i))) {
+ // If the entire vector is undefined, just return this info.
+ UndefElts = EltMask;
+ return nullptr;
+ }
+ if (I->getOperand(i)->getType()->isVectorTy()) {
+ APInt UndefEltsOp(VWidth, 0);
+ simplifyAndSetOp(I, i, DemandedElts, UndefEltsOp);
+ UndefElts |= UndefEltsOp;
+ }
+ }
break;
}
@@ -1663,5 +1672,10 @@ Value *InstCombiner::SimplifyDemandedVec
UndefElts &= UndefElts2;
}
+ // If we've proven all of the lanes undef, return an undef value.
+ // TODO: Intersect w/demanded lanes
+ if (UndefElts.isAllOnesValue())
+ return UndefValue::get(I->getType());;
+
return MadeChange ? I : nullptr;
}
Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=356293&r1=356292&r2=356293&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Fri Mar 15 12:54:06 2019
@@ -1557,6 +1557,19 @@ Instruction *InstCombiner::visitGetEleme
if (Value *V = SimplifyGEPInst(GEPEltType, Ops, SQ.getWithInstruction(&GEP)))
return replaceInstUsesWith(GEP, V);
+ // For vector geps, use the generic demanded vector support.
+ if (GEP.getType()->isVectorTy()) {
+ auto VWidth = GEP.getType()->getVectorNumElements();
+ APInt UndefElts(VWidth, 0);
+ APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
+ if (Value *V = SimplifyDemandedVectorElts(&GEP, AllOnesEltMask,
+ UndefElts)) {
+ if (V != &GEP)
+ return replaceInstUsesWith(GEP, V);
+ return &GEP;
+ }
+ }
+
Value *PtrOp = GEP.getOperand(0);
// Eliminate unneeded casts for indices, and replace indices which displace
Modified: llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll?rev=356293&r1=356292&r2=356293&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll Fri Mar 15 12:54:06 2019
@@ -620,10 +620,7 @@ define i32* @gep_splat_both(i32* %base,
define <2 x i32*> @gep_all_lanes_undef(i32* %base, i64 %idx) {;
; CHECK-LABEL: @gep_all_lanes_undef(
-; CHECK-NEXT: [[BASEVEC:%.*]] = insertelement <2 x i32*> undef, i32* [[BASE:%.*]], i32 0
-; CHECK-NEXT: [[IDXVEC:%.*]] = insertelement <2 x i64> undef, i64 [[IDX:%.*]], i32 1
-; CHECK-NEXT: [[GEP:%.*]] = getelementptr i32, <2 x i32*> [[BASEVEC]], <2 x i64> [[IDXVEC]]
-; CHECK-NEXT: ret <2 x i32*> [[GEP]]
+; CHECK-NEXT: ret <2 x i32*> undef
;
%basevec = insertelement <2 x i32*> undef, i32* %base, i32 0
%idxvec = insertelement <2 x i64> undef, i64 %idx, i32 1
@@ -641,4 +638,3 @@ define i32* @gep_demanded_lane_undef(i32
%ee = extractelement <2 x i32*> %gep, i32 1
ret i32* %ee
}
-
More information about the llvm-commits
mailing list