Rework to adjust m_ImmConstant

Author: lukel97

llvm/include/llvm/IR/PatternMatch.h

@@ -858,18 +858,51 @@ inline bind_ty<const BasicBlock> m_BasicBlock(const BasicBlock *&V) {
   return V;
 }
 
+// TODO: Remove once UseConstant{Int,FP}ForScalableSplat is enabled by default,
+// and use m_Unless(m_ConstantExpr).
+struct immconstant_ty {
+  template <typename ITy> static bool isImmConstant(ITy *V) {
+    if (auto *CV = dyn_cast<Constant>(V)) {
+      if (!isa<ConstantExpr>(CV) && !CV->containsConstantExpression())
+        return true;
+
+      if (CV->getType()->isVectorTy()) {
+        if (auto *Splat = CV->getSplatValue(/* AllowPoison */ true)) {
+          if (!isa<ConstantExpr>(Splat) &&
+              !Splat->containsConstantExpression()) {
+            return true;
+          }
+        }
+      }
+    }
+    return false;
+  }
+};
+
+struct match_immconstant_ty : immconstant_ty {
+  template <typename ITy> bool match(ITy *V) { return isImmConstant(V); }
+};
+
 /// Match an arbitrary immediate Constant and ignore it.
-inline match_combine_and<class_match<Constant>,
-                         match_unless<constantexpr_match>>
-m_ImmConstant() {
-  return m_CombineAnd(m_Constant(), m_Unless(m_ConstantExpr()));
-}
+inline match_immconstant_ty m_ImmConstant() { return match_immconstant_ty(); }
+
+struct bind_immconstant_ty : immconstant_ty {
+  Constant *&VR;
+
+  bind_immconstant_ty(Constant *&V) : VR(V) {}
+
+  template <typename ITy> bool match(ITy *V) {
+    if (isImmConstant(V)) {
+      VR = cast<Constant>(V);
+      return true;
+    }
+    return false;
+  }
+};
 
 /// Match an immediate Constant, capturing the value if we match.
-inline match_combine_and<bind_ty<Constant>,
-                         match_unless<constantexpr_match>>
-m_ImmConstant(Constant *&C) {
-  return m_CombineAnd(m_Constant(C), m_Unless(m_ConstantExpr()));
+inline bind_immconstant_ty m_ImmConstant(Constant *&C) {
+  return bind_immconstant_ty(C);
 }
 
 /// Match a specified Value*.

llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp

@@ -428,10 +428,7 @@ Instruction *InstCombinerImpl::commonShiftTransforms(BinaryOperator &I) {
         return R;
 
   Constant *CUI;
-  if (match(Op1, m_Constant(CUI)) &&
-      (!isa<ConstantExpr>(CUI) ||
-       (Ty->isVectorTy() &&
-        isa_and_present<ConstantInt>(CUI->getSplatValue()))))
+  if (match(Op1, m_ImmConstant(CUI)))
     if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
       return Res;
 

llvm/test/Transforms/InstCombine/select.ll

@@ -3519,8 +3519,7 @@ define <vscale x 2 x i32> @scalable_sign_bits(<vscale x 2 x i8> %x) {
 
 define <vscale x 2 x i1> @scalable_non_zero(<vscale x 2 x i32> %x) {
 ; CHECK-LABEL: @scalable_non_zero(
-; CHECK-NEXT:    [[A:%.*]] = or <vscale x 2 x i32> [[X:%.*]], splat (i32 1)
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult <vscale x 2 x i32> [[A]], splat (i32 57)
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult <vscale x 2 x i32> [[X:%.*]], splat (i32 56)
 ; CHECK-NEXT:    ret <vscale x 2 x i1> [[CMP]]
 ;
   %a = or <vscale x 2 x i32> %x, splat (i32 1)

llvm/test/Transforms/InstCombine/sub.ll

@@ -861,7 +861,7 @@ define <2 x i16> @test44vecminval(<2 x i16> %x) {
 ; uses m_ImmConstant which matches Constant but (explicitly) not ConstantExpr.
 define <vscale x 2 x i16> @test44scalablevecminval(<vscale x 2 x i16> %x) {
 ; CHECK-LABEL: @test44scalablevecminval(
-; CHECK-NEXT:    [[SUB:%.*]] = add <vscale x 2 x i16> [[X:%.*]], splat (i16 -32768)
+; CHECK-NEXT:    [[SUB:%.*]] = xor <vscale x 2 x i16> [[X:%.*]], splat (i16 -32768)
 ; CHECK-NEXT:    ret <vscale x 2 x i16> [[SUB]]
 ;
   %sub = sub nsw <vscale x 2 x i16> %x, splat (i16 -32768)