if (F->doesNotAccessMemory())
return FMRB_DoesNotAccessMemory;
+ // While the assume intrinsic is marked as arbitrarily writing so that
+ // proper control dependencies will be maintained, it never aliases any
+ // particular memory location.
+ if (F->getIntrinsicID() == Intrinsic::assume)
+ return FMRB_DoesNotAccessMemory;
+
FunctionModRefBehavior Min = FMRB_UnknownModRefBehavior;
// If the function declares it only reads memory, go with that.
--- /dev/null
+; RUN: opt -basicaa -print-memoryssa -verify-memoryssa -analyze < %s 2>&1 | FileCheck %s
+;
+; Ensures that assumes are treated as not reading or writing memory.
+
+declare void @llvm.assume(i1)
+
+define i32 @foo(i32* %a, i32* %b, i1 %c) {
+; CHECK: 1 = MemoryDef(liveOnEntry)
+; CHECK-NEXT: store i32 4
+ store i32 4, i32* %a, align 4
+; CHECK: call void @llvm.assume
+ call void @llvm.assume(i1 %c)
+; CHECK: MemoryUse(1)
+; CHECK-NEXT: %1 = load i32
+ %1 = load i32, i32* %a, align 4
+ ret i32 %1
+}