[llvm-commits] [llvm-gcc-4.2] r41071 - /llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp

[Chris Lattner]

Author: lattner
Date: Tue Aug 14 10:45:39 2007
New Revision: 41071

URL: http://llvm.org/viewvc/llvm-project?rev=41071&view=rev
Log:
When building casts, constant fold with ConstantFoldInstruction instead
of ConstantExpr::getCast.  This allows target-data driven constant folding
to happen.  In the testcase from PR1602, for example, this results in:

        %tmp26 = sub i32 %tmp232425, 1          

instead of:

        %tmp26 = sub i32 %tmp232425, ptrtoint (i32 (...)** inttoptr (i64 1 to i32 (...)**) to i32)



Modified:
    llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp

Modified: llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp?rev=41071&r1=41070&r2=41071&view=diff

==============================================================================
--- llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp (original)
+++ llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp Tue Aug 14 10:45:39 2007
@@ -34,6 +34,7 @@
 #include "llvm/InlineAsm.h"
 #include "llvm/Instructions.h"
 #include "llvm/Module.h"
+#include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Target/TargetAsmInfo.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetMachine.h"
@@ -1045,16 +1046,26 @@
   if (V->getType() == Ty) 
     return V;
 
+  // If this is a simple constant operand, fold it now.  If it is a constant
+  // expr operand, fold it below.
   if (Constant *C = dyn_cast<Constant>(V))
-    return ConstantExpr::getCast(Instruction::CastOps(opcode), C, Ty);
+    if (!isa<ConstantExpr>(C))
+      return ConstantExpr::getCast(Instruction::CastOps(opcode), C, Ty);
   
   // Handle 'trunc (zext i1 X to T2) to i1' as X, because this occurs all over
   // the place.
   if (ZExtInst *CI = dyn_cast<ZExtInst>(V))
     if (Ty == Type::Int1Ty && CI->getOperand(0)->getType() == Type::Int1Ty)
       return CI->getOperand(0);
-  return Builder.CreateCast(Instruction::CastOps(opcode), V, Ty,
-                            V->getName().c_str());
+  Value *Result = Builder.CreateCast(Instruction::CastOps(opcode), V, Ty,
+                                     V->getNameStart());
+
+  // If this is a constantexpr, fold the instruction with
+  // ConstantFoldInstruction to allow TargetData-driven folding to occur.
+  if (isa<ConstantExpr>(V))
+    Result = ConstantFoldInstruction(cast<Instruction>(Result), &TD);
+  
+  return Result;
 }
 
 /// CastToAnyType - Cast the specified value to the specified type making no