[llvm] r370583 - [X86ISelLowering] combineCMov - cleanup CMOV->LEA codegen. NFCI.

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Sat Aug 31 07:18:26 2019
New Revision: 370583

URL: http://llvm.org/viewvc/llvm-project?rev=370583&view=rev
Log:
[X86ISelLowering] combineCMov - cleanup CMOV->LEA codegen. NFCI.

Only compute the diff once and we don't need the truncation code (assert the bitwidth is correct just to be safe).

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=370583&r1=370582&r2=370583&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Sat Aug 31 07:18:26 2019
@@ -37537,12 +37537,13 @@ static SDValue combineCMov(SDNode *N, Se
       // Optimize cases that will turn into an LEA instruction.  This requires
       // an i32 or i64 and an efficient multiplier (1, 2, 3, 4, 5, 8, 9).
       if (N->getValueType(0) == MVT::i32 || N->getValueType(0) == MVT::i64) {
-        uint64_t Diff = TrueC->getZExtValue()-FalseC->getZExtValue();
-        if (N->getValueType(0) == MVT::i32) Diff = (unsigned)Diff;
+        APInt Diff = TrueC->getAPIntValue() - FalseC->getAPIntValue();
+        assert(Diff.getBitWidth() == N->getValueType(0).getSizeInBits() &&
+               "Implicit constant truncation");
 
         bool isFastMultiplier = false;
-        if (Diff < 10) {
-          switch ((unsigned char)Diff) {
+        if (Diff.ult(10)) {
+          switch (Diff.getZExtValue()) {
           default: break;
           case 1:  // result = add base, cond
           case 2:  // result = lea base(    , cond*2)
@@ -37557,7 +37558,6 @@ static SDValue combineCMov(SDNode *N, Se
         }
 
         if (isFastMultiplier) {
-          APInt Diff = TrueC->getAPIntValue()-FalseC->getAPIntValue();
           Cond = getSETCC(CC, Cond, DL ,DAG);
           // Zero extend the condition if needed.
           Cond = DAG.getNode(ISD::ZERO_EXTEND, DL, FalseC->getValueType(0),