[llvm] 89a2a47 - [InstCombine] Add m_SpecificIntAllowUndef pattern matcher

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2020-10-14T16:15:53+01:00
New Revision: 89a2a478708fb8821fb88ef3053e8d6bb5b59e08

URL: https://github.com/llvm/llvm-project/commit/89a2a478708fb8821fb88ef3053e8d6bb5b59e08
DIFF: https://github.com/llvm/llvm-project/commit/89a2a478708fb8821fb88ef3053e8d6bb5b59e08.diff

LOG: [InstCombine] Add m_SpecificIntAllowUndef pattern matcher

m_SpecificInt doesn't accept undef elements in a vector splat value - tweak specific_intval to optionally allow undefs and add the m_SpecificIntAllowUndef variants.

Allows us to remove the m_APIntAllowUndef + comparison hack inside matchFunnelShift

Added: 
    

Modified: 
    llvm/include/llvm/IR/PatternMatch.h
    llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index 000a3af4cc2c..85a358f09014 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -705,6 +705,7 @@ struct bind_const_intval_ty {
 
 /// Match a specified integer value or vector of all elements of that
 /// value.
+template <bool AllowUndefs>
 struct specific_intval {
   APInt Val;
 
@@ -714,7 +715,7 @@ struct specific_intval {
     const auto *CI = dyn_cast<ConstantInt>(V);
     if (!CI && V->getType()->isVectorTy())
       if (const auto *C = dyn_cast<Constant>(V))
-        CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue());
+        CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue(AllowUndefs));
 
     return CI && APInt::isSameValue(CI->getValue(), Val);
   }
@@ -722,14 +723,22 @@ struct specific_intval {
 
 /// Match a specific integer value or vector with all elements equal to
 /// the value.
-inline specific_intval m_SpecificInt(APInt V) {
-  return specific_intval(std::move(V));
+inline specific_intval<false> m_SpecificInt(APInt V) {
+  return specific_intval<false>(std::move(V));
 }
 
-inline specific_intval m_SpecificInt(uint64_t V) {
+inline specific_intval<false> m_SpecificInt(uint64_t V) {
   return m_SpecificInt(APInt(64, V));
 }
 
+inline specific_intval<true> m_SpecificIntAllowUndef(APInt V) {
+  return specific_intval<true>(std::move(V));
+}
+
+inline specific_intval<true> m_SpecificIntAllowUndef(uint64_t V) {
+  return m_SpecificIntAllowUndef(APInt(64, V));
+}
+
 /// Match a ConstantInt and bind to its value.  This does not match
 /// ConstantInts wider than 64-bits.
 inline bind_const_intval_ty m_ConstantInt(uint64_t &V) { return V; }

diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 7f5f05d04139..c19982ec0098 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2090,13 +2090,11 @@ static Instruction *matchFunnelShift(Instruction &Or, InstCombinerImpl &IC) {
       if (LI->ult(Width) && RI->ult(Width) && (*LI + *RI) == Width)
         return ConstantInt::get(L->getType(), *LI);
 
-    const APInt *SumC;
     Constant *LC, *RC;
     if (match(L, m_Constant(LC)) && match(R, m_Constant(RC)) &&
         match(L, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
         match(R, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
-        match(ConstantExpr::getAdd(LC, RC), m_APIntAllowUndef(SumC)) &&
-        *SumC == Width)
+        match(ConstantExpr::getAdd(LC, RC), m_SpecificIntAllowUndef(Width)))
       return ConstantExpr::mergeUndefsWith(LC, RC);
 
     // (shl ShVal, X) | (lshr ShVal, (Width - x)) iff X < Width.