[llvm] [LICM] Rewrite noConflictingReadWrites to walk MemorySSA graph (PR #191468)

[via llvm-commits]

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@@ -0,0 +1,207 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -aa-pipeline=basic-aa -passes='require<aa>,require<target-ir>,loop-mssa(licm)' < %s -S | FileCheck %s
+
+;; It should hoist fn_write_inaccessible_mem
+;; because there is no conflict between inaccessible memory and argmem
+define dso_local i32 @hoist_inaccessible_with_argmem(i32 %x, ptr %a, ptr %b) #0 {
+; CHECK-LABEL: define dso_local i32 @hoist_inaccessible_with_argmem(
+; CHECK-SAME: i32 [[X:%.*]], ptr [[A:%.*]], ptr [[B:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[VAL:%.*]] = getelementptr inbounds nuw i32, ptr [[A]], i64 1
+; CHECK-NEXT:    call void @fn_write_inaccessible_mem()
+; CHECK-NEXT:    call void @fn_read_inaccessible_mem()
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[PHI:%.*]] = phi ptr [ [[GEP:%.*]], %[[LOOP]] ], [ [[VAL]], %[[ENTRY]] ]
+; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr i8, ptr [[PHI]], i64 0
+; CHECK-NEXT:    [[VAL2:%.*]] = call i32 @fn_args(ptr [[GEP2]])
+; CHECK-NEXT:    [[GEP]] = getelementptr inbounds nuw i32, ptr [[PHI]], i64 0
+; CHECK-NEXT:    [[ACC:%.*]] = add nuw nsw i32 [[VAL2]], 1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[ACC]], 10
+; CHECK-NEXT:    br i1 [[CMP]], label %[[LOOP]], label %[[AFTER_LOOP:.*]]
+; CHECK:       [[AFTER_LOOP]]:
+; CHECK-NEXT:    [[ACC_LCSSA:%.*]] = phi i32 [ [[ACC]], %[[LOOP]] ]
+; CHECK-NEXT:    ret i32 [[ACC_LCSSA]]
+;
+entry:
+  %val = getelementptr inbounds nuw i32, ptr %a, i64 1
+  br label %loop
+loop:
+  %phi = phi ptr [ %gep, %loop ], [ %val, %entry ]
+  %44 = load i32, ptr %phi, align 16
+  %gep2 = getelementptr i8, ptr %phi, i64 0
+  %val2 = call i32 @fn_args(ptr  %gep2)
+  call void @fn_write_inaccessible_mem()
+  call void @fn_read_inaccessible_mem()
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CarolineConcatto wrote:

If you replace : 
call void @fn_read_inaccessible_mem()
by 
call void @fn_read_inaccessible_mem(i32 %val2)

we dont need the tests for hoist-aarch64-fpmr.ll and hoist_inaccessible_past_load.
Because they are all checking the same thing

https://github.com/llvm/llvm-project/pull/191468