[llvm] 8d0fdd3 - [IR] CmpInst: Add getFlippedSignednessPredicate()

[Roman Lebedev via llvm-commits]

Author: Roman Lebedev
Date: 2020-11-06T11:31:09+03:00
New Revision: 8d0fdd36a3a3e7d1bb07c34ab61cfe2671d13444

URL: https://github.com/llvm/llvm-project/commit/8d0fdd36a3a3e7d1bb07c34ab61cfe2671d13444
DIFF: https://github.com/llvm/llvm-project/commit/8d0fdd36a3a3e7d1bb07c34ab61cfe2671d13444.diff

LOG: [IR] CmpInst: Add getFlippedSignednessPredicate()

And refactor a few places to use it

Added: 
    

Modified: 
    llvm/include/llvm/IR/InstrTypes.h
    llvm/lib/IR/Instructions.cpp
    llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/IR/InstrTypes.h b/llvm/include/llvm/IR/InstrTypes.h
index 27575487e7ab..5d3b603ad01b 100644
--- a/llvm/include/llvm/IR/InstrTypes.h
+++ b/llvm/include/llvm/IR/InstrTypes.h
@@ -942,6 +942,18 @@ class CmpInst : public Instruction {
     return getUnsignedPredicate(getPredicate());
   }
 
+  /// For example, SLT->ULT, ULT->SLT, SLE->ULE, ULE->SLE, EQ->Failed assert
+  /// @returns the unsigned version of the signed predicate pred or
+  ///          the signed version of the signed predicate pred.
+  static Predicate getFlippedSignednessPredicate(Predicate pred);
+
+  /// For example, SLT->ULT, ULT->SLT, SLE->ULE, ULE->SLE, EQ->Failed assert
+  /// @returns the unsigned version of the signed predicate pred or
+  ///          the signed version of the signed predicate pred.
+  Predicate getFlippedSignednessPredicate() {
+    return getFlippedSignednessPredicate(getPredicate());
+  }
+
   /// This is just a convenience.
   /// Determine if this is true when both operands are the same.
   bool isTrueWhenEqual() const {

diff  --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 43588aa7f6d5..7a5670dc100b 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -3898,6 +3898,18 @@ bool CmpInst::isSigned(Predicate predicate) {
   }
 }
 
+CmpInst::Predicate CmpInst::getFlippedSignednessPredicate(Predicate pred) {
+  assert(CmpInst::isRelational(pred) &&
+         "Call only with non-equality predicates!");
+
+  if (isSigned(pred))
+    return getUnsignedPredicate(pred);
+  if (isUnsigned(pred))
+    return getSignedPredicate(pred);
+
+  llvm_unreachable("Unknown predicate!");
+}
+
 bool CmpInst::isOrdered(Predicate predicate) {
   switch (predicate) {
     default: return false;

diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index fe342dc2fc6c..ddd4754a5e6c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1614,15 +1614,13 @@ Instruction *InstCombinerImpl::foldICmpXorConstant(ICmpInst &Cmp,
   if (Xor->hasOneUse()) {
     // (icmp u/s (xor X SignMask), C) -> (icmp s/u X, (xor C SignMask))
     if (!Cmp.isEquality() && XorC->isSignMask()) {
-      Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
-                            : Cmp.getSignedPredicate();
+      Pred = Cmp.getFlippedSignednessPredicate();
       return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), C ^ *XorC));
     }
 
     // (icmp u/s (xor X ~SignMask), C) -> (icmp s/u X, (xor C ~SignMask))
     if (!Cmp.isEquality() && XorC->isMaxSignedValue()) {
-      Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
-                            : Cmp.getSignedPredicate();
+      Pred = Cmp.getFlippedSignednessPredicate();
       Pred = Cmp.getSwappedPredicate(Pred);
       return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), C ^ *XorC));
     }
@@ -4053,15 +4051,13 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
       if (match(BO0->getOperand(1), m_APInt(C))) {
         // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
         if (C->isSignMask()) {
-          ICmpInst::Predicate NewPred =
-              I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate();
+          ICmpInst::Predicate NewPred = I.getFlippedSignednessPredicate();
           return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
         }
 
         // icmp u/s (a ^ maxsignval), (b ^ maxsignval) --> icmp s/u' a, b
         if (BO0->getOpcode() == Instruction::Xor && C->isMaxSignedValue()) {
-          ICmpInst::Predicate NewPred =
-              I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate();
+          ICmpInst::Predicate NewPred = I.getFlippedSignednessPredicate();
           NewPred = I.getSwappedPredicate(NewPred);
           return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
         }