[llvm] r260612 - Re-apply r238452, the bug was in clang and was fixed in r260567.

[Quentin Colombet via llvm-commits]

Author: qcolombet
Date: Thu Feb 11 16:30:41 2016
New Revision: 260612

URL: http://llvm.org/viewvc/llvm-project?rev=260612&view=rev
Log:
Re-apply r238452, the bug was in clang and was fixed in r260567.

Original commit message:
[InstCombine] Fold IntToPtr and PtrToInt into preceding loads.

Currently we only fold a BitCast into a Load when the BitCast is its
only user.

Do the same for any no-op cast.

Patch by Philip Pfaffe!

Differential Revision: http://reviews.llvm.org/D9152

Added:
    llvm/trunk/test/Transforms/InstCombine/load-bitcast32.ll
      - copied unchanged from r259673, llvm/trunk/test/Transforms/InstCombine/load-bitcast32.ll
    llvm/trunk/test/Transforms/InstCombine/load-bitcast64.ll
      - copied unchanged from r259673, llvm/trunk/test/Transforms/InstCombine/load-bitcast64.ll
Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
    llvm/trunk/test/Transforms/InstCombine/memset_chk-1.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp?rev=260612&r1=260611&r2=260612&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp Thu Feb 11 16:30:41 2016
@@ -495,12 +495,17 @@ static Instruction *combineLoadToOperati
   }
 
   // Fold away bit casts of the loaded value by loading the desired type.
+  // We can do this for BitCastInsts as well as casts from and to pointer types,
+  // as long as those are noops (i.e., the source or dest type have the same
+  // bitwidth as the target's pointers).
   if (LI.hasOneUse())
-    if (auto *BC = dyn_cast<BitCastInst>(LI.user_back())) {
-      LoadInst *NewLoad = combineLoadToNewType(IC, LI, BC->getDestTy());
-      BC->replaceAllUsesWith(NewLoad);
-      IC.eraseInstFromFunction(*BC);
-      return &LI;
+    if (auto* CI = dyn_cast<CastInst>(LI.user_back())) {
+      if (CI->isNoopCast(DL)) {
+        LoadInst *NewLoad = combineLoadToNewType(IC, LI, CI->getDestTy());
+        CI->replaceAllUsesWith(NewLoad);
+        IC.eraseInstFromFunction(*CI);
+        return &LI;
+      }
     }
 
   // FIXME: We should also canonicalize loads of vectors when their elements are

Modified: llvm/trunk/test/Transforms/InstCombine/memset_chk-1.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/memset_chk-1.ll?rev=260612&r1=260611&r2=260612&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/memset_chk-1.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/memset_chk-1.ll Thu Feb 11 16:30:41 2016
@@ -72,14 +72,14 @@ entry:
   %yo107 = call i64 @llvm.objectsize.i64.p0i8(i8* %b, i1 false)
   %call50 = call i8* @__memmove_chk(i8* %b, i8* %a, i64 %add180, i64 %yo107)
 ; CHECK: %strlen = call i64 @strlen(i8* %b)
-; CHECK-NEXT: [[STRCHR:%[0-9a-zA-Z_-]+]] = getelementptr i8, i8* %b, i64 %strlen
+; CHECK-NEXT: %strchr2 = getelementptr i8, i8* %b, i64 %strlen
   %call51i = call i8* @strrchr(i8* %b, i32 0)
   %d = load i8*, i8** %c, align 8
   %sub182 = ptrtoint i8* %d to i64
   %sub183 = ptrtoint i8* %b to i64
   %sub184 = sub i64 %sub182, %sub183
   %add52.i.i = add nsw i64 %sub184, 1
-; CHECK: call void @llvm.memset.p0i8.i64(i8* [[STRCHR]]
+; CHECK: call void @llvm.memset.p0i8.i64(i8* %strchr2
   %call185 = call i8* @__memset_chk(i8* %call51i, i32 0, i64 %add52.i.i, i64 -1)
   ret i32 4
 }