[llvm-commits] [llvm] r53151 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/cast-mul-select.ll

[Nick Lewycky]

Author: nicholas
Date: Sat Jul  5 16:19:34 2008
New Revision: 53151

URL: http://llvm.org/viewvc/llvm-project?rev=53151&view=rev
Log:
Fix missed optimization opportunity when analyzing cast of mul and select.

Added:
    llvm/trunk/test/Transforms/InstCombine/cast-mul-select.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=53151&r1=53150&r2=53151&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Sat Jul  5 16:19:34 2008
@@ -6917,6 +6917,7 @@
   switch (I->getOpcode()) {
   case Instruction::Add:
   case Instruction::Sub:
+  case Instruction::Mul:
   case Instruction::And:
   case Instruction::Or:
   case Instruction::Xor:
@@ -6926,14 +6927,6 @@
            CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
                                       NumCastsRemoved);
 
-  case Instruction::Mul:
-    // A multiply can be truncated by truncating its operands.
-    return Ty->getBitWidth() < OrigTy->getBitWidth() && 
-           CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
-                                      NumCastsRemoved) &&
-           CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
-                                      NumCastsRemoved);
-
   case Instruction::Shl:
     // If we are truncating the result of this SHL, and if it's a shift of a
     // constant amount, we can always perform a SHL in a smaller type.
@@ -6970,7 +6963,13 @@
     if (I->getOpcode() == CastOpc)
       return true;
     break;
-      
+  case Instruction::Select: {
+    SelectInst *SI = cast<SelectInst>(I);
+    return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
+                                      NumCastsRemoved) &&
+           CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
+                                      NumCastsRemoved);
+  }
   case Instruction::PHI: {
     // We can change a phi if we can change all operands.
     PHINode *PN = cast<PHINode>(I);
@@ -7028,6 +7027,12 @@
     Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
                            Ty);
     break;
+  case Instruction::Select: {
+    Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
+    Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
+    Res = SelectInst::Create(I->getOperand(0), True, False);
+    break;
+  }
   case Instruction::PHI: {
     PHINode *OPN = cast<PHINode>(I);
     PHINode *NPN = PHINode::Create(Ty);

Added: llvm/trunk/test/Transforms/InstCombine/cast-mul-select.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/cast-mul-select.ll?rev=53151&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/cast-mul-select.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/cast-mul-select.ll Sat Jul  5 16:19:34 2008
@@ -0,0 +1,29 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | notcast
+
+define i32 @mul(i32 %x, i32 %y) {
+  %A = trunc i32 %x to i8
+  %B = trunc i32 %y to i8
+  %C = mul i8 %A, %B
+  %D = zext i8 %C to i32
+  ret i32 %D
+}
+
+define i32 @select1(i1 %cond, i32 %x, i32 %y, i32 %z) {
+  %A = trunc i32 %x to i8
+  %B = trunc i32 %y to i8
+  %C = trunc i32 %z to i8
+  %D = add i8 %A, %B
+  %E = select i1 %cond, i8 %C, i8 %D
+  %F = zext i8 %E to i32
+  ret i32 %F
+}
+
+define i8 @select2(i1 %cond, i8 %x, i8 %y, i8 %z) {
+  %A = zext i8 %x to i32
+  %B = zext i8 %y to i32
+  %C = zext i8 %z to i32
+  %D = add i32 %A, %B
+  %E = select i1 %cond, i32 %C, i32 %D
+  %F = trunc i32 %E to i8
+  ret i8 %F
+}