[llvm] [BoundsChecking] Handle vscale allocas (PR #90926)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: Vitaly Buka (vitalybuka)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/90926.diff


2 Files Affected:

- (modified) llvm/lib/Analysis/MemoryBuiltins.cpp (+4-4) 
- (modified) llvm/test/Instrumentation/BoundsChecking/simple.ll (+66) 


``````````diff
diff --git a/llvm/lib/Analysis/MemoryBuiltins.cpp b/llvm/lib/Analysis/MemoryBuiltins.cpp
index 46a7a921d86d3d..8ca15434833d9d 100644
--- a/llvm/lib/Analysis/MemoryBuiltins.cpp
+++ b/llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -1138,8 +1138,8 @@ SizeOffsetValue ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
   if (!I.getAllocatedType()->isSized())
     return ObjectSizeOffsetEvaluator::unknown();
 
-  // must be a VLA
-  assert(I.isArrayAllocation());
+  // must be a VLA or vscale.
+  assert(I.isArrayAllocation() || I.getAllocatedType()->isScalableTy());
 
   // If needed, adjust the alloca's operand size to match the pointer indexing
   // size. Subsequent math operations expect the types to match.
@@ -1149,8 +1149,8 @@ SizeOffsetValue ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
   assert(ArraySize->getType() == Zero->getType() &&
          "Expected zero constant to have pointer index type");
 
-  Value *Size = ConstantInt::get(ArraySize->getType(),
-                                 DL.getTypeAllocSize(I.getAllocatedType()));
+  Value *Size = Builder.CreateTypeSize(
+      ArraySize->getType(), DL.getTypeAllocSize(I.getAllocatedType()));
   Size = Builder.CreateMul(Size, ArraySize);
   return SizeOffsetValue(Size, Zero);
 }
diff --git a/llvm/test/Instrumentation/BoundsChecking/simple.ll b/llvm/test/Instrumentation/BoundsChecking/simple.ll
index 60d124f0b89735..914cafdc57f9d3 100644
--- a/llvm/test/Instrumentation/BoundsChecking/simple.ll
+++ b/llvm/test/Instrumentation/BoundsChecking/simple.ll
@@ -488,3 +488,69 @@ define <vscale x 1 x i32> @load_scalable_vector(i64 %y) nounwind {
   %3 = load <vscale x 1 x i32>, ptr %2, align 8
   ret <vscale x 1 x i32> %3
 }
+
+define void @scalable_alloca(i64 %y) nounwind {
+; CHECK-LABEL: @scalable_alloca(
+; CHECK-NEXT:    [[TMP1:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT:    [[TMP2:%.*]] = mul i64 [[TMP1]], 8
+; CHECK-NEXT:    [[TMP3:%.*]] = mul i64 [[TMP2]], 5
+; CHECK-NEXT:    [[TMP4:%.*]] = alloca <vscale x 4 x i16>, i32 5, align 8
+; CHECK-NEXT:    [[TMP5:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT:    [[TMP6:%.*]] = mul i64 [[TMP5]], 8
+; CHECK-NEXT:    [[DOTIDX:%.*]] = mul i64 [[Y:%.*]], [[TMP6]]
+; CHECK-NEXT:    [[TMP7:%.*]] = add i64 0, [[DOTIDX]]
+; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds <vscale x 4 x i16>, ptr [[TMP4]], i64 [[Y]]
+; CHECK-NEXT:    [[TMP9:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT:    [[TMP10:%.*]] = mul i64 [[TMP9]], 8
+; CHECK-NEXT:    [[TMP11:%.*]] = sub i64 [[TMP3]], [[TMP7]]
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult i64 [[TMP3]], [[TMP7]]
+; CHECK-NEXT:    [[TMP13:%.*]] = icmp ult i64 [[TMP11]], [[TMP10]]
+; CHECK-NEXT:    [[TMP14:%.*]] = or i1 [[TMP12]], [[TMP13]]
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp slt i64 [[TMP7]], 0
+; CHECK-NEXT:    [[TMP16:%.*]] = or i1 [[TMP15]], [[TMP14]]
+; CHECK-NEXT:    br i1 [[TMP16]], label [[TRAP:%.*]], label [[TMP17:%.*]]
+; CHECK:       17:
+; CHECK-NEXT:    [[TMP18:%.*]] = load <vscale x 4 x i16>, ptr [[TMP8]], align 4
+; CHECK-NEXT:    ret void
+; CHECK:       trap:
+; CHECK-NEXT:    call void @llvm.trap() #[[ATTR6]]
+; CHECK-NEXT:    unreachable
+;
+  %1 = alloca <vscale x 4 x i16>, i32 5
+  %2 = getelementptr inbounds <vscale x 4 x i16>, ptr %1, i64 %y
+  %3 = load <vscale x 4 x i16>, ptr %2, align 4
+  ret void
+}
+
+define void @scalable_alloca2(i64 %y) nounwind {
+; CHECK-LABEL: @scalable_alloca2(
+; CHECK-NEXT:    [[TMP1:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT:    [[TMP2:%.*]] = mul i64 [[TMP1]], 32
+; CHECK-NEXT:    [[TMP3:%.*]] = mul i64 [[TMP2]], 1
+; CHECK-NEXT:    [[TMP4:%.*]] = alloca <vscale x 4 x i64>, align 32
+; CHECK-NEXT:    [[TMP5:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT:    [[TMP6:%.*]] = mul i64 [[TMP5]], 32
+; CHECK-NEXT:    [[DOTIDX:%.*]] = mul i64 [[Y:%.*]], [[TMP6]]
+; CHECK-NEXT:    [[TMP7:%.*]] = add i64 0, [[DOTIDX]]
+; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds <vscale x 4 x i64>, ptr [[TMP4]], i64 [[Y]]
+; CHECK-NEXT:    [[TMP9:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT:    [[TMP10:%.*]] = mul i64 [[TMP9]], 32
+; CHECK-NEXT:    [[TMP11:%.*]] = sub i64 [[TMP3]], [[TMP7]]
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult i64 [[TMP3]], [[TMP7]]
+; CHECK-NEXT:    [[TMP13:%.*]] = icmp ult i64 [[TMP11]], [[TMP10]]
+; CHECK-NEXT:    [[TMP14:%.*]] = or i1 [[TMP12]], [[TMP13]]
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp slt i64 [[TMP7]], 0
+; CHECK-NEXT:    [[TMP16:%.*]] = or i1 [[TMP15]], [[TMP14]]
+; CHECK-NEXT:    br i1 [[TMP16]], label [[TRAP:%.*]], label [[TMP17:%.*]]
+; CHECK:       17:
+; CHECK-NEXT:    [[TMP18:%.*]] = load <vscale x 4 x i64>, ptr [[TMP8]], align 4
+; CHECK-NEXT:    ret void
+; CHECK:       trap:
+; CHECK-NEXT:    call void @llvm.trap() #[[ATTR6]]
+; CHECK-NEXT:    unreachable
+;
+  %1 = alloca <vscale x 4 x i64>
+  %2 = getelementptr inbounds <vscale x 4 x i64>, ptr %1, i64 %y
+  %3 = load <vscale x 4 x i64>, ptr %2, align 4
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/90926