[InstCombine] Support ssub.sat canonicalization for non-splats
Extend ssub.sat(X, C) -> sadd.sat(X, -C) canonicalization to also
support non-splat vector constants. This is done by generalizing
the implementation of the isNotMinSignedValue() helper to return
true for constants that are non-splat, but don't contain any
signed min elements.
Differential Revision: https://reviews.llvm.org/D55011
llvm-svn: 348072
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 0410c75..aa1d6c9 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -184,18 +184,15 @@
if (const ConstantFP *CFP = dyn_cast<ConstantFP>(this))
return !CFP->getValueAPF().bitcastToAPInt().isMinSignedValue();
- // Check for constant vectors which are splats of INT_MIN values.
- if (const ConstantVector *CV = dyn_cast<ConstantVector>(this))
- if (Constant *Splat = CV->getSplatValue())
- return Splat->isNotMinSignedValue();
-
- // Check for constant vectors which are splats of INT_MIN values.
- if (const ConstantDataVector *CV = dyn_cast<ConstantDataVector>(this)) {
- if (CV->isSplat()) {
- if (CV->getElementType()->isFloatingPointTy())
- return !CV->getElementAsAPFloat(0).bitcastToAPInt().isMinSignedValue();
- return !CV->getElementAsAPInt(0).isMinSignedValue();
+ // Check that vectors don't contain INT_MIN
+ if (this->getType()->isVectorTy()) {
+ unsigned NumElts = this->getType()->getVectorNumElements();
+ for (unsigned i = 0; i != NumElts; ++i) {
+ Constant *Elt = this->getAggregateElement(i);
+ if (!Elt || !Elt->isNotMinSignedValue())
+ return false;
}
+ return true;
}
// It *may* contain INT_MIN, we can't tell.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index f0b09e1..a023b6d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -2104,11 +2104,10 @@
}
// ssub.sat(X, C) -> sadd.sat(X, -C) if C != MIN
- // TODO: Support non-splat C.
- const APInt *C;
- if (IID == Intrinsic::ssub_sat && match(Arg1, m_APInt(C)) &&
- !C->isMinSignedValue()) {
- Value *NegVal = ConstantInt::get(II->getType(), -*C);
+ Constant *C;
+ if (IID == Intrinsic::ssub_sat && match(Arg1, m_Constant(C)) &&
+ C->isNotMinSignedValue()) {
+ Value *NegVal = ConstantExpr::getNeg(C);
return replaceInstUsesWith(
*II, Builder.CreateBinaryIntrinsic(
Intrinsic::sadd_sat, Arg0, NegVal));
diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
index 060ecf4..51f2670 100644
--- a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
+++ b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
@@ -337,11 +337,10 @@
ret <2 x i8> %r
}
-; Canonicalization for non-splat constants is not supported yet.
define <2 x i8> @test_vector_ssub_canonical_min_non_splat(<2 x i8> %a) {
; CHECK-LABEL: @test_vector_ssub_canonical_min_non_splat(
-; CHECK-NEXT: [[R:%.*]] = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> [[A:%.*]], <2 x i8> <i8 10, i8 -10>)
-; CHECK-NEXT: ret <2 x i8> [[R]]
+; CHECK-NEXT: [[TMP1:%.*]] = call <2 x i8> @llvm.sadd.sat.v2i8(<2 x i8> [[A:%.*]], <2 x i8> <i8 -10, i8 10>)
+; CHECK-NEXT: ret <2 x i8> [[TMP1]]
;
%r = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> %a, <2 x i8> <i8 10, i8 -10>)
ret <2 x i8> %r
@@ -630,8 +629,8 @@
define <2 x i8> @test_vector_ssub_neg_nneg(<2 x i8> %a) {
; CHECK-LABEL: @test_vector_ssub_neg_nneg(
; CHECK-NEXT: [[A_NEG:%.*]] = or <2 x i8> [[A:%.*]], <i8 -128, i8 -128>
-; CHECK-NEXT: [[R:%.*]] = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> [[A_NEG]], <2 x i8> <i8 10, i8 20>)
-; CHECK-NEXT: ret <2 x i8> [[R]]
+; CHECK-NEXT: [[TMP1:%.*]] = call <2 x i8> @llvm.sadd.sat.v2i8(<2 x i8> [[A_NEG]], <2 x i8> <i8 -10, i8 -20>)
+; CHECK-NEXT: ret <2 x i8> [[TMP1]]
;
%a_neg = or <2 x i8> %a, <i8 -128, i8 -128>
%r = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> %a_neg, <2 x i8> <i8 10, i8 20>)