[clang] [flang] [flang] Enable alias tags pass by default (PR #73111)

[Tom Eccles via cfe-commits]

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@@ -2,12 +2,25 @@
 ! See flang/test/Fir/tbaa-codegen.fir for a test that the output is correct
 
 ! RUN: %flang -c -emit-llvm -falias-analysis %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-! RUN: %flang -c -emit-llvm -falias-analysis -fno-alias-analysis %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
+! RUN: %flang -c -emit-llvm -Ofast %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
+! RUN: %flang -c -emit-llvm -O3 %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
+! RUN: %flang -c -emit-llvm -O2 %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
+! RUN: %flang -c -emit-llvm -O1 %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
+
+! RUN: %flang -c -emit-llvm -O0 %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
+! RUN: %flang -c -emit-llvm -Ofast -fno-alias-analysis %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
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tblah wrote:

I have added a test in this case. `-fno-alias-analysis` takes precedence over `-Ofast` no matter their order.

I don't think there is anything in clang that is equivalent to `-f[no-]alias-analysis`. These flags were added to flang so we could upstream alias analysis without enabling it by default. I would like to keep them after enabling by default in case alias analysis leads to any regressions.

https://github.com/llvm/llvm-project/pull/73111