[PATCH] D129561: [RS4GC] Fix over-restrictive assert in atomic memcpy/move handling

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.
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The existing code doesn't expect dummy values (undef, null etc) as arguments of these
intrinsics. However, they can be there in unreached code. Currently we fail trying to find
base for them.

The fix is to take the pointer itself as the base if it's not found in map. Should not matter
in any real practical situation.


https://reviews.llvm.org/D129561

Files:
  llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
  llvm/test/Transforms/RewriteStatepointsForGC/pr56493.ll


Index: llvm/test/Transforms/RewriteStatepointsForGC/pr56493.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/RewriteStatepointsForGC/pr56493.ll
@@ -0,0 +1,18 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=rewrite-statepoints-for-gc -S < %s | FileCheck %s
+
+; Make sure this doesn't crash.
+define void @test() gc "statepoint-example" personality i32* ()* @zot {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[STATEPOINT_TOKEN:%.*]] = call token (i64, i32, void (i32 addrspace(1)*, i64, i32 addrspace(1)*, i64, i64)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidp1i32i64p1i32i64i64f(i64 2882400000, i32 0, void (i32 addrspace(1)*, i64, i32 addrspace(1)*, i64, i64)* elementtype(void (i32 addrspace(1)*, i64, i32 addrspace(1)*, i64, i64)) @__llvm_memcpy_element_unordered_atomic_safepoint_4, i32 5, i32 0, i32 addrspace(1)* undef, i64 undef, i32 addrspace(1)* bitcast (i8 addrspace(1)* getelementptr inbounds (i8, i8 addrspace(1)* null, i64 16) to i32 addrspace(1)*), i64 sub (i64 ptrtoint (i8 addrspace(1)* getelementptr inbounds (i8, i8 addrspace(1)* null, i64 16) to i64), i64 ptrtoint (i8 addrspace(1)* getelementptr inbounds (i8, i8 addrspace(1)* null, i64 16) to i64)), i64 undef, i32 0, i32 0) [ "deopt"() ]
+; CHECK-NEXT:    ret void
+;
+bb:
+  call void @llvm.memcpy.element.unordered.atomic.p1i32.p1i32.i64(i32 addrspace(1)* elementtype(i32) align 8 undef, i32 addrspace(1)* elementtype(i32) align 16 bitcast (i8 addrspace(1)* getelementptr inbounds (i8, i8 addrspace(1)* null, i64 16) to i32 addrspace(1)*), i64 undef, i32 4) #3 [ "deopt"() ]
+  ret void
+}
+
+declare i32* @zot()
+
+declare void @llvm.memcpy.element.unordered.atomic.p1i32.p1i32.i64(i32 addrspace(1)* nocapture writeonly, i32 addrspace(1)* nocapture readonly, i64, i32 immarg)
Index: llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1702,10 +1702,10 @@
       auto &Context = Call->getContext();
       auto &DL = Call->getModule()->getDataLayout();
       auto GetBaseAndOffset = [&](Value *Derived) {
-        assert(PointerToBase.count(Derived));
         unsigned AddressSpace = Derived->getType()->getPointerAddressSpace();
         unsigned IntPtrSize = DL.getPointerSizeInBits(AddressSpace);
-        Value *Base = PointerToBase.find(Derived)->second;
+        auto It = PointerToBase.find(Derived);
+        Value *Base = It != PointerToBase.end() ? It->second : Derived;
         Value *Base_int = Builder.CreatePtrToInt(
             Base, Type::getIntNTy(Context, IntPtrSize));
         Value *Derived_int = Builder.CreatePtrToInt(


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