[llvm-commits] [llvm] r69809 - /llvm/trunk/lib/Analysis/ScalarEvolution.cpp

[Dan Gohman]

Author: djg
Date: Wed Apr 22 11:20:48 2009
New Revision: 69809

URL: http://llvm.org/viewvc/llvm-project?rev=69809&view=rev
Log:
Simplify trivial cast-of-cast SCEVs.

Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=69809&r1=69808&r2=69809&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Wed Apr 22 11:20:48 2009
@@ -654,6 +654,10 @@
     return getUnknown(
         ConstantExpr::getTrunc(SC->getValue(), Ty));
 
+  // trunc(trunc(x)) --> trunc(x)
+  if (SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
+    return getTruncateExpr(ST->getOperand(), Ty);
+
   // If the input value is a chrec scev made out of constants, truncate
   // all of the constants.
   if (SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
@@ -685,6 +689,10 @@
     return getUnknown(C);
   }
 
+  // zext(zext(x)) --> zext(x)
+  if (SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
+    return getZeroExtendExpr(SZ->getOperand(), Ty);
+
   // FIXME: If the input value is a chrec scev, and we can prove that the value
   // did not overflow the old, smaller, value, we can zero extend all of the
   // operands (often constants).  This would allow analysis of something like
@@ -706,6 +714,10 @@
     return getUnknown(C);
   }
 
+  // sext(sext(x)) --> sext(x)
+  if (SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
+    return getSignExtendExpr(SS->getOperand(), Ty);
+
   // FIXME: If the input value is a chrec scev, and we can prove that the value
   // did not overflow the old, smaller, value, we can sign extend all of the
   // operands (often constants).  This would allow analysis of something like