[llvm-commits] [llvm] r124547 - in /llvm/trunk: lib/VMCore/ConstantFold.cpp test/Transforms/ConstProp/constant-expr.ll

[Nick Lewycky]

Author: nicholas
Date: Sat Jan 29 14:35:06 2011
New Revision: 124547

URL: http://llvm.org/viewvc/llvm-project?rev=124547&view=rev
Log:
Add the select optimization recently added to instcombine to constant folding.
This is the one where one of the branches of the select is another select on
the same condition.

Modified:
    llvm/trunk/lib/VMCore/ConstantFold.cpp
    llvm/trunk/test/Transforms/ConstProp/constant-expr.ll

Modified: llvm/trunk/lib/VMCore/ConstantFold.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/ConstantFold.cpp?rev=124547&r1=124546&r2=124547&view=diff
==============================================================================
--- llvm/trunk/lib/VMCore/ConstantFold.cpp (original)
+++ llvm/trunk/lib/VMCore/ConstantFold.cpp Sat Jan 29 14:35:06 2011
@@ -693,6 +693,18 @@
   if (isa<UndefValue>(V2)) return V1;
   if (isa<UndefValue>(Cond)) return V1;
   if (V1 == V2) return V1;
+
+  if (ConstantExpr *TrueVal = dyn_cast<ConstantExpr>(V1)) {
+    if (TrueVal->getOpcode() == Instruction::Select)
+      if (TrueVal->getOperand(0) == Cond)
+	return ConstantExpr::getSelect(Cond, TrueVal->getOperand(1), V2);
+  }
+  if (ConstantExpr *FalseVal = dyn_cast<ConstantExpr>(V2)) {
+    if (FalseVal->getOpcode() == Instruction::Select)
+      if (FalseVal->getOperand(0) == Cond)
+	return ConstantExpr::getSelect(Cond, V1, FalseVal->getOperand(2));
+  }
+
   return 0;
 }
 

Modified: llvm/trunk/test/Transforms/ConstProp/constant-expr.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ConstProp/constant-expr.ll?rev=124547&r1=124546&r2=124547&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ConstProp/constant-expr.ll (original)
+++ llvm/trunk/test/Transforms/ConstProp/constant-expr.ll Sat Jan 29 14:35:06 2011
@@ -100,3 +100,12 @@
 ; CHECK: pr9011_14 = constant i128 0
 @pr9011_15 = constant i128 bitcast (<4 x i32> zeroinitializer to i128)
 ; CHECK: pr9011_15 = constant i128 0
+
+ at select = internal constant
+          i32 select (i1 icmp ult (i32 ptrtoint (i8* @X to i32),
+                                   i32 ptrtoint (i8* @Y to i32)),
+            i32 select (i1 icmp ult (i32 ptrtoint (i8* @X to i32),
+                                     i32 ptrtoint (i8* @Y to i32)),
+               i32 10, i32 20),
+            i32 30)
+; CHECK: select = internal constant i32 select {{.*}} i32 10, i32 30