3 files changed, 82 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 56212b04eb0..54b1af8ea79 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -417,6 +417,35 @@ static Instruction *combineLoadToOperationType(InstCombiner &IC, LoadInst &LI) {
   if (LI.use_empty())
     return nullptr;
 
+  Type *Ty = LI.getType();
+
+  // Try to canonicalize loads which are only ever stored to operate over
+  // integers instead of any other type. We only do this when the loaded type
+  // is sized and has a size exactly the same as its store size and the store
+  // size is a legal integer type.
+  const DataLayout *DL = IC.getDataLayout();
+  if (!Ty->isIntegerTy() && Ty->isSized() && DL &&
+      DL->isLegalInteger(DL->getTypeStoreSizeInBits(Ty)) &&
+      DL->getTypeStoreSizeInBits(Ty) == DL->getTypeSizeInBits(Ty)) {
+    if (std::all_of(LI.user_begin(), LI.user_end(), [&LI](User *U) {
+          auto *SI = dyn_cast<StoreInst>(U);
+          return SI && SI->getPointerOperand() != &LI;
+        })) {
+      LoadInst *NewLoad = combineLoadToNewType(
+          IC, LI,
+          Type::getIntNTy(LI.getContext(), DL->getTypeStoreSizeInBits(Ty)));
+      // Replace all the stores with stores of the newly loaded value.
+      for (auto UI = LI.user_begin(), UE = LI.user_end(); UI != UE;) {
+        auto *SI = cast<StoreInst>(*UI++);
+        IC.Builder->SetInsertPoint(SI);
+        combineStoreToNewValue(IC, *SI, NewLoad);
+        IC.EraseInstFromFunction(*SI);
+      }
+      assert(LI.use_empty() && "Failed to remove all users of the load!");
+      // Return the old load so the combiner can delete it safely.
+      return &LI;
+    }
+  }
 
   // Fold away bit casts of the loaded value by loading the desired type.
   if (LI.hasOneUse())
diff --git a/llvm/test/Transforms/InstCombine/load.ll b/llvm/test/Transforms/InstCombine/load.ll
index b4b7558a1a0..700797ab22c 100644
--- a/llvm/test/Transforms/InstCombine/load.ll
+++ b/llvm/test/Transforms/InstCombine/load.ll
@@ -2,7 +2,7 @@
 
 ; This test makes sure that these instructions are properly eliminated.
 
-target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target datalayout = "e-m:e-p:64:64:64-i64:64-f80:128-n8:16:32:64-S128"
 
 @X = constant i32 42		; <i32*> [#uses=2]
 @X2 = constant i32 47		; <i32*> [#uses=1]
@@ -150,3 +150,53 @@ define i8 @test15(i8 %x, i32 %y) {
   %r = load i8* %g.i8
   ret i8 %r
 }
+
+define void @test16(i8* %x, i8* %a, i8* %b, i8* %c) {
+; Check that we canonicalize loads which are only stored to use integer types
+; when there is a valid integer type.
+; CHECK-LABEL: @test16(
+; CHECK: %[[L1:.*]] = load i32*
+; CHECK-NOT: load
+; CHECK: store i32 %[[L1]], i32*
+; CHECK: store i32 %[[L1]], i32*
+; CHECK-NOT: store
+; CHECK: %[[L1:.*]] = load i32*
+; CHECK-NOT: load
+; CHECK: store i32 %[[L1]], i32*
+; CHECK: store i32 %[[L1]], i32*
+; CHECK-NOT: store
+; CHECK: ret
+
+entry:
+  %x.cast = bitcast i8* %x to float*
+  %a.cast = bitcast i8* %a to float*
+  %b.cast = bitcast i8* %b to float*
+  %c.cast = bitcast i8* %c to i32*
+
+  %x1 = load float* %x.cast
+  store float %x1, float* %a.cast
+  store float %x1, float* %b.cast
+
+  %x2 = load float* %x.cast
+  store float %x2, float* %b.cast
+  %x2.cast = bitcast float %x2 to i32
+  store i32 %x2.cast, i32* %c.cast
+
+  ret void
+}
+
+define void @test17(i8** %x, i8 %y) {
+; Check that in cases similar to @test16 we don't try to rewrite a load when
+; its only use is a store but it is used as the pointer to that store rather
+; than the value.
+;
+; CHECK-LABEL: @test17(
+; CHECK: %[[L:.*]] = load i8**
+; CHECK: store i8 %y, i8* %[[L]]
+
+entry:
+  %x.load = load i8** %x
+  store i8 %y, i8* %x.load
+
+  ret void
+}
diff --git a/llvm/test/Transforms/InstCombine/struct-assign-tbaa.ll b/llvm/test/Transforms/InstCombine/struct-assign-tbaa.ll
index 4e4b3f2a1a8..e949640d261 100644
--- a/llvm/test/Transforms/InstCombine/struct-assign-tbaa.ll
+++ b/llvm/test/Transforms/InstCombine/struct-assign-tbaa.ll
@@ -10,8 +10,8 @@ declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32,
 %struct.test1 = type { float }
 
 ; CHECK: @test
-; CHECK: %2 = load float* %0, align 4, !tbaa !0
-; CHECK: store float %2, float* %1, align 4, !tbaa !0
+; CHECK: %[[LOAD:.*]] = load i32* %{{.*}}, align 4, !tbaa !0
+; CHECK: store i32 %[[LOAD:.*]], i32* %{{.*}}, align 4, !tbaa !0
 ; CHECK: ret
 define void @test1(%struct.test1* nocapture %a, %struct.test1* nocapture %b) {
 entry: