[llvm] aff1863 - [IR] Remove ConstantExpr::getUMin() (NFC)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-03-06T13:16:27+01:00
New Revision: aff18638591b40dbba51e9e9f75973a242bcb276

URL: https://github.com/llvm/llvm-project/commit/aff18638591b40dbba51e9e9f75973a242bcb276
DIFF: https://github.com/llvm/llvm-project/commit/aff18638591b40dbba51e9e9f75973a242bcb276.diff

LOG: [IR] Remove ConstantExpr::getUMin() (NFC)

This is part of select constant expression removal. As there is
only a single place where this is used, just expand it to explicit
constant folding calls.

(Normally we'd just use the IRBuilder here, but this isn't possible
due to mergeUndefsWith use).

Added: 
    

Modified: 
    llvm/include/llvm/IR/Constants.h
    llvm/lib/IR/Constants.cpp
    llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/IR/Constants.h b/llvm/include/llvm/IR/Constants.h
index 8aaedc3d082b0..b5e68054a1aea 100644
--- a/llvm/include/llvm/IR/Constants.h
+++ b/llvm/include/llvm/IR/Constants.h
@@ -1049,7 +1049,6 @@ class ConstantExpr : public Constant {
   static Constant *getAnd(Constant *C1, Constant *C2);
   static Constant *getOr(Constant *C1, Constant *C2);
   static Constant *getXor(Constant *C1, Constant *C2);
-  static Constant *getUMin(Constant *C1, Constant *C2);
   static Constant *getShl(Constant *C1, Constant *C2, bool HasNUW = false,
                           bool HasNSW = false);
   static Constant *getLShr(Constant *C1, Constant *C2, bool isExact = false);

diff  --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 6e25e224b1dbc..6a6209c37d393 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -2690,11 +2690,6 @@ Constant *ConstantExpr::getXor(Constant *C1, Constant *C2) {
   return get(Instruction::Xor, C1, C2);
 }
 
-Constant *ConstantExpr::getUMin(Constant *C1, Constant *C2) {
-  Constant *Cmp = ConstantExpr::getICmp(CmpInst::ICMP_ULT, C1, C2);
-  return getSelect(Cmp, C1, C2);
-}
-
 Constant *ConstantExpr::getShl(Constant *C1, Constant *C2,
                                bool HasNUW, bool HasNSW) {
   unsigned Flags = (HasNUW ? OverflowingBinaryOperator::NoUnsignedWrap : 0) |

diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index f399810ead2f6..2130177e8cf87 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -918,11 +918,18 @@ Instruction *InstCombinerImpl::visitTrunc(TruncInst &Trunc) {
     // removed by the trunc.
     if (match(C, m_SpecificInt_ICMP(ICmpInst::ICMP_ULE,
                                     APInt(SrcWidth, MaxShiftAmt)))) {
+      auto GetNewShAmt = [&](unsigned Width) {
+        Constant *MaxAmt = ConstantInt::get(SrcTy, Width - 1, false);
+        Constant *Cmp =
+            ConstantFoldCompareInstOperands(ICmpInst::ICMP_ULT, C, MaxAmt, DL);
+        Constant *ShAmt = ConstantFoldSelectInstruction(Cmp, C, MaxAmt);
+        return ConstantFoldCastOperand(Instruction::Trunc, ShAmt, A->getType(),
+                                       DL);
+      };
+
       // trunc (lshr (sext A), C) --> ashr A, C
       if (A->getType() == DestTy) {
-        Constant *MaxAmt = ConstantInt::get(SrcTy, DestWidth - 1, false);
-        Constant *ShAmt = ConstantExpr::getUMin(C, MaxAmt);
-        ShAmt = ConstantExpr::getTrunc(ShAmt, A->getType());
+        Constant *ShAmt = GetNewShAmt(DestWidth);
         ShAmt = Constant::mergeUndefsWith(ShAmt, C);
         return IsExact ? BinaryOperator::CreateExactAShr(A, ShAmt)
                        : BinaryOperator::CreateAShr(A, ShAmt);
@@ -930,9 +937,7 @@ Instruction *InstCombinerImpl::visitTrunc(TruncInst &Trunc) {
       // The types are mismatched, so create a cast after shifting:
       // trunc (lshr (sext A), C) --> sext/trunc (ashr A, C)
       if (Src->hasOneUse()) {
-        Constant *MaxAmt = ConstantInt::get(SrcTy, AWidth - 1, false);
-        Constant *ShAmt = ConstantExpr::getUMin(C, MaxAmt);
-        ShAmt = ConstantExpr::getTrunc(ShAmt, A->getType());
+        Constant *ShAmt = GetNewShAmt(AWidth);
         Value *Shift = Builder.CreateAShr(A, ShAmt, "", IsExact);
         return CastInst::CreateIntegerCast(Shift, DestTy, true);
       }