From 62d327e241f59735eed836e98c8f11ffaa6cf6f8 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Thu, 22 Oct 2009 06:38:35 +0000
Subject: [PATCH] move 'loading i32 from string' optimization from instcombine
 to libanalysis.  Instcombine shrinking... does this even make sense???

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84840 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/ConstantFolding.cpp              | 41 ++++++++++++++++---
 .../Scalar/InstructionCombining.cpp           | 34 ---------------
 2 files changed, 35 insertions(+), 40 deletions(-)

diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index da671c8f5d8..1f91ddf3789 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -24,13 +24,13 @@
 #include "llvm/Instructions.h"
 #include "llvm/Intrinsics.h"
 #include "llvm/LLVMContext.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Target/TargetData.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
-#include "llvm/Target/TargetData.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/GetElementPtrTypeIterator.h"
 #include "llvm/Support/MathExtras.h"
-#include "llvm/GlobalVariable.h"
 #include <cerrno>
 #include <cmath>
 using namespace llvm;
@@ -111,6 +111,35 @@ Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C,
                ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
             return V;
     }
+    
+    // Instead of loading constant c string, use corresponding integer value
+    // directly if string length is small enough.
+    std::string Str;
+    if (TD && GetConstantStringInfo(CE->getOperand(0), Str) && !Str.empty()) {
+      unsigned len = Str.length();
+      const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
+      unsigned numBits = Ty->getPrimitiveSizeInBits();
+      // Replace LI with immediate integer store.
+      if ((numBits >> 3) == len + 1) {
+        APInt StrVal(numBits, 0);
+        APInt SingleChar(numBits, 0);
+        if (TD->isLittleEndian()) {
+          for (signed i = len-1; i >= 0; i--) {
+            SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
+            StrVal = (StrVal << 8) | SingleChar;
+          }
+        } else {
+          for (unsigned i = 0; i < len; i++) {
+            SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
+            StrVal = (StrVal << 8) | SingleChar;
+          }
+          // Append NULL at the end.
+          SingleChar = 0;
+          StrVal = (StrVal << 8) | SingleChar;
+        }
+        return ConstantInt::get(CE->getContext(), StrVal);
+      }
+    }
   }
 
   return 0;
@@ -675,15 +704,15 @@ Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
           C = UndefValue::get(ATy->getElementType());
         else
           return 0;
-      } else if (const VectorType *PTy = dyn_cast<VectorType>(*I)) {
-        if (CI->getZExtValue() >= PTy->getNumElements())
+      } else if (const VectorType *VTy = dyn_cast<VectorType>(*I)) {
+        if (CI->getZExtValue() >= VTy->getNumElements())
           return 0;
         if (ConstantVector *CP = dyn_cast<ConstantVector>(C))
           C = CP->getOperand(CI->getZExtValue());
         else if (isa<ConstantAggregateZero>(C))
-          C = Constant::getNullValue(PTy->getElementType());
+          C = Constant::getNullValue(VTy->getElementType());
         else if (isa<UndefValue>(C))
-          C = UndefValue::get(PTy->getElementType());
+          C = UndefValue::get(VTy->getElementType());
         else
           return 0;
       } else {
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index dd313ac5163..62cd532f44e 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -11345,40 +11345,6 @@ static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
   Value *CastOp = CI->getOperand(0);
   LLVMContext *Context = IC.getContext();
 
-  if (TD) {
-    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(CI)) {
-      // Instead of loading constant c string, use corresponding integer value
-      // directly if string length is small enough.
-      std::string Str;
-      if (GetConstantStringInfo(CE->getOperand(0), Str) && !Str.empty()) {
-        unsigned len = Str.length();
-        const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
-        unsigned numBits = Ty->getPrimitiveSizeInBits();
-        // Replace LI with immediate integer store.
-        if ((numBits >> 3) == len + 1) {
-          APInt StrVal(numBits, 0);
-          APInt SingleChar(numBits, 0);
-          if (TD->isLittleEndian()) {
-            for (signed i = len-1; i >= 0; i--) {
-              SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
-              StrVal = (StrVal << 8) | SingleChar;
-            }
-          } else {
-            for (unsigned i = 0; i < len; i++) {
-              SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
-              StrVal = (StrVal << 8) | SingleChar;
-            }
-            // Append NULL at the end.
-            SingleChar = 0;
-            StrVal = (StrVal << 8) | SingleChar;
-          }
-          Value *NL = ConstantInt::get(*Context, StrVal);
-          return IC.ReplaceInstUsesWith(LI, NL);
-        }
-      }
-    }
-  }
-
   const PointerType *DestTy = cast<PointerType>(CI->getType());
   const Type *DestPTy = DestTy->getElementType();
   if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
-- 
2.34.1