[llvm] [LAA] Rewrite findForkedPointer, fixing freeze (PR #140298)

[Florian Hahn via llvm-commits]

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@@ -169,16 +171,12 @@ define void @test_loop_dependent_select2(ptr %src.1, ptr %src.2, ptr %dst, i8 %n
 ; CHECK-NEXT:    [[TMP5:%.*]] = add nuw nsw i64 [[TMP4]], 1
 ; CHECK-NEXT:    [[UGLYGEP:%.*]] = getelementptr i8, ptr [[DST:%.*]], i64 [[TMP5]]
 ; CHECK-NEXT:    [[UGLYGEP1:%.*]] = getelementptr i8, ptr [[SRC_1:%.*]], i64 1
-; CHECK-NEXT:    [[SRC_1_FR:%.*]] = freeze ptr [[SRC_1]]
-; CHECK-NEXT:    [[UGLYGEP1_FR:%.*]] = freeze ptr [[UGLYGEP1]]
 ; CHECK-NEXT:    [[UGLYGEP2:%.*]] = getelementptr i8, ptr [[SRC_2:%.*]], i64 1
-; CHECK-NEXT:    [[SRC_2_FR:%.*]] = freeze ptr [[SRC_2]]
-; CHECK-NEXT:    [[UGLYGEP2_FR:%.*]] = freeze ptr [[UGLYGEP2]]
-; CHECK-NEXT:    [[BOUND0:%.*]] = icmp ult ptr [[DST]], [[UGLYGEP1_FR]]
-; CHECK-NEXT:    [[BOUND1:%.*]] = icmp ult ptr [[SRC_1_FR]], [[UGLYGEP]]
+; CHECK-NEXT:    [[BOUND0:%.*]] = icmp ult ptr [[DST]], [[UGLYGEP1]]
+; CHECK-NEXT:    [[BOUND1:%.*]] = icmp ult ptr [[SRC_1]], [[UGLYGEP]]
 ; CHECK-NEXT:    [[FOUND_CONFLICT:%.*]] = and i1 [[BOUND0]], [[BOUND1]]
-; CHECK-NEXT:    [[BOUND03:%.*]] = icmp ult ptr [[DST]], [[UGLYGEP2_FR]]
-; CHECK-NEXT:    [[BOUND14:%.*]] = icmp ult ptr [[SRC_2_FR]], [[UGLYGEP]]
+; CHECK-NEXT:    [[BOUND03:%.*]] = icmp ult ptr [[DST]], [[UGLYGEP2]]
+; CHECK-NEXT:    [[BOUND14:%.*]] = icmp ult ptr [[SRC_2]], [[UGLYGEP]]
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fhahn wrote:

Freezes of SRC_1/SRC_2 should be needed, as either may be poison and not dereferenced in the loop, so w/o freeze we could introduce new branch on poison?

https://github.com/llvm/llvm-project/pull/140298