[SROA] Avoid splitting loads/stores with irregular type

Upon encountering loads/stores on types whose size is not a multiple of 8 bits the SROA pass would either trip an assertion or use logic that was not meant to work with such irregularly-sized types.

Reviewed By: aeubanks

Differential Revision: https://reviews.llvm.org/D99435

Author: LemonBoy

llvm/lib/Transforms/Scalar/SROA.cpp

@@ -768,7 +768,8 @@ class AllocaSlices::SliceBuilder : public PtrUseVisitor<SliceBuilder> {
     // We allow splitting of non-volatile loads and stores where the type is an
     // integer type. These may be used to implement 'memcpy' or other "transfer
     // of bits" patterns.
-    bool IsSplittable = Ty->isIntegerTy() && !IsVolatile;
+    bool IsSplittable =
+        Ty->isIntegerTy() && !IsVolatile && DL.typeSizeEqualsStoreSize(Ty);
 
     insertUse(I, Offset, Size, IsSplittable);
   }
@@ -3989,6 +3990,7 @@ bool SROA::presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS) {
     SplitLoads.clear();
 
     IntegerType *Ty = cast<IntegerType>(LI->getType());
+    assert(Ty->getBitWidth() % 8 == 0);
     uint64_t LoadSize = Ty->getBitWidth() / 8;
     assert(LoadSize > 0 && "Cannot have a zero-sized integer load!");
 
@@ -4113,6 +4115,7 @@ bool SROA::presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS) {
   for (StoreInst *SI : Stores) {
     auto *LI = cast<LoadInst>(SI->getValueOperand());
     IntegerType *Ty = cast<IntegerType>(LI->getType());
+    assert(Ty->getBitWidth() % 8 == 0);
     uint64_t StoreSize = Ty->getBitWidth() / 8;
     assert(StoreSize > 0 && "Cannot have a zero-sized integer store!");
 

llvm/test/Transforms/SROA/irregular-type.ll

@@ -0,0 +1,48 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -sroa -S | FileCheck %s
+
+%S = type { [4 x i8] }
+
+; Ensure the load/store of integer types whose size is not equal to the store
+; size are not split.
+
+define i8 @foo(i23 %0) {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT:  Entry:
+; CHECK-NEXT:    [[DOTSROA_0:%.*]] = alloca [3 x i8], align 8
+; CHECK-NEXT:    [[DOTSROA_0_0__SROA_CAST1:%.*]] = bitcast [3 x i8]* [[DOTSROA_0]] to i23*
+; CHECK-NEXT:    store i23 [[TMP0:%.*]], i23* [[DOTSROA_0_0__SROA_CAST1]], align 8
+; CHECK-NEXT:    [[DOTSROA_0_1__SROA_IDX2:%.*]] = getelementptr inbounds [3 x i8], [3 x i8]* [[DOTSROA_0]], i64 0, i64 1
+; CHECK-NEXT:    [[DOTSROA_0_1__SROA_0_1_:%.*]] = load i8, i8* [[DOTSROA_0_1__SROA_IDX2]], align 1
+; CHECK-NEXT:    ret i8 [[DOTSROA_0_1__SROA_0_1_]]
+;
+Entry:
+  %1 = alloca %S
+  %2 = bitcast %S* %1 to i23*
+  store i23 %0, i23* %2
+  %3 = getelementptr inbounds %S, %S* %1, i64 0, i32 0, i32 1
+  %4 = load i8, i8* %3
+  ret i8 %4
+}
+
+define i32 @bar(i16 %0) {
+; CHECK-LABEL: @bar(
+; CHECK-NEXT:  Entry:
+; CHECK-NEXT:    [[DOTSROA_0:%.*]] = alloca [3 x i8], align 8
+; CHECK-NEXT:    [[DOTSROA_0_0__SROA_CAST2:%.*]] = bitcast [3 x i8]* [[DOTSROA_0]] to i16*
+; CHECK-NEXT:    store i16 [[TMP0:%.*]], i16* [[DOTSROA_0_0__SROA_CAST2]], align 8
+; CHECK-NEXT:    [[DOTSROA_0_0_Q_SROA_CAST1:%.*]] = bitcast [3 x i8]* [[DOTSROA_0]] to i17*
+; CHECK-NEXT:    [[DOTSROA_0_0__SROA_0_0_:%.*]] = load i17, i17* [[DOTSROA_0_0_Q_SROA_CAST1]], align 8
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i17 [[DOTSROA_0_0__SROA_0_0_]] to i32
+; CHECK-NEXT:    ret i32 [[TMP1]]
+;
+Entry:
+  %1 = alloca %S
+  %2 = bitcast %S* %1 to i16*
+  store i16 %0, i16* %2
+  %3 = getelementptr inbounds %S, %S* %1, i64 0, i32 0
+  %q = bitcast [4 x i8]* %3 to i17*
+  %4 = load i17, i17* %q
+  %5 = zext i17 %4 to i32
+  ret i32 %5
+}