[llvm-commits] [llvm] r124469 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineSelect.cpp test/Transforms/InstCombine/select.ll

[Nick Lewycky]

Author: nicholas
Date: Thu Jan 27 21:28:10 2011
New Revision: 124469

URL: http://llvm.org/viewvc/llvm-project?rev=124469&view=rev
Log:
Fold select + select where both selects are on the same condition.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp
    llvm/trunk/test/Transforms/InstCombine/select.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp?rev=124469&r1=124468&r2=124469&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp Thu Jan 27 21:28:10 2011
@@ -792,6 +792,19 @@
       if (Instruction *NV = FoldOpIntoPhi(SI))
         return NV;
 
+  if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
+    if (TrueSI->getCondition() == CondVal) {
+      SI.setOperand(1, TrueSI->getTrueValue());
+      return &SI;
+    }
+  }
+  if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
+    if (FalseSI->getCondition() == CondVal) {
+      SI.setOperand(2, FalseSI->getFalseValue());
+      return &SI;
+    }
+  }
+
   if (BinaryOperator::isNot(CondVal)) {
     SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
     SI.setOperand(1, FalseVal);

Modified: llvm/trunk/test/Transforms/InstCombine/select.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/select.ll?rev=124469&r1=124468&r2=124469&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/select.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/select.ll Thu Jan 27 21:28:10 2011
@@ -692,7 +692,7 @@
 
 ; PR8994
 
-; Theis select instruction can't be eliminated because trying to do so would
+; This select instruction can't be eliminated because trying to do so would
 ; change the number of vector elements. This used to assert.
 define i48 @test51(<3 x i1> %icmp, <3 x i16> %tmp) {
   %select = select <3 x i1> %icmp, <3 x i16> zeroinitializer, <3 x i16> %tmp
@@ -700,3 +700,18 @@
   %tmp2 = bitcast <3 x i16> %select to i48
   ret i48 %tmp2
 }
+
+; PR8575
+
+ at g = common global i32 0, align 4
+define void @test52(i32 %n, i32 %m) nounwind {
+entry:
+  %cmp = icmp sgt i32 %n, %m
+  %. = select i1 %cmp, i32 1, i32 3
+  %add = add nsw i32 %., 3
+  %storemerge = select i1 %cmp, i32 %., i32 %add
+; CHECK: select i1 %cmp, i32 1, i32 6
+  store i32 %storemerge, i32* @g, align 4
+  ret void
+}
+