commit d5d3e9013dcb2f875cb6718ecece8715c4df1212
author Reid Spencer <rspencer@reidspencer.com> Thu Jan 18 18:54:33 2007 +0000
committer Copybara-Service <copybara-worker@google.com> Wed Sep 23 05:45:30 2020 -0700
tree 77334722041325016654a99dddde1de1d87a8722
parent d163446004fcf1acd5b6a9082a984f0e6122d6bf

Clean up some code around the store V, (cast P) -> store (cast V), P
transform. Change some variable names so it is clear what is source and
what is dest of the cast. Also, add an assert to ensure that the integer
to integer case is asserting if the bitwidths are different. This prevents
illegal casts from being formed and catches bitwidth bugs sooner.

llvm-svn: 33337
GitOrigin-RevId: c050af91264264006fcdb6fdacd3a36283628d09

lib/Transforms/Scalar/InstructionCombining.cpp

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index f81f10e..48eaef5 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -8186,23 +8186,29 @@
                IC.getTargetData().getTypeSize(DestPTy)) {
 
         // Okay, we are casting from one integer or pointer type to another of
-        // the same size.  Instead of casting the pointer before the store, cast
-        // the value to be stored.
+        // the same size.  Instead of casting the pointer before 
+        // the store, cast the value to be stored.
         Value *NewCast;
-        Instruction::CastOps opcode = Instruction::BitCast;
         Value *SIOp0 = SI.getOperand(0);
-        if (isa<PointerType>(SrcPTy)) {
-          if (SIOp0->getType()->isInteger())
+        Instruction::CastOps opcode = Instruction::BitCast;
+        const Type* CastSrcTy = SIOp0->getType();
+        const Type* CastDstTy = SrcPTy;
+        if (isa<PointerType>(CastDstTy)) {
+          if (CastSrcTy->isInteger())
             opcode = Instruction::IntToPtr;
-        } else if (SrcPTy->isInteger()) {
+        } else if (const IntegerType* DITy = dyn_cast<IntegerType>(CastDstTy)) {
           if (isa<PointerType>(SIOp0->getType()))
             opcode = Instruction::PtrToInt;
+          else if (const IntegerType* SITy = dyn_cast<IntegerType>(CastSrcTy))
+            assert(DITy->getBitWidth() == SITy->getBitWidth() &&
+                   "Illegal store instruction");
         }
         if (Constant *C = dyn_cast<Constant>(SIOp0))
-          NewCast = ConstantExpr::getCast(opcode, C, SrcPTy);
+          NewCast = ConstantExpr::getCast(opcode, C, CastDstTy);
         else
           NewCast = IC.InsertNewInstBefore(
-            CastInst::create(opcode, SIOp0, SrcPTy, SIOp0->getName()+".c"), SI);
+            CastInst::create(opcode, SIOp0, CastDstTy, SIOp0->getName()+".c"), 
+            SI);
         return new StoreInst(NewCast, CastOp);
       }
     }