[flang] remove -f[no-]alias-analysis (#74343)

tblah · web-flow · commit 6b8d659062a0 · 2023-12-05T10:03:57.000Z
Now that tbaa tags pass is enabled by default, I would like to remove these flags. `-fno-alias-analysis` was originally intended to be useful for debugging, but as it also disables tbaa tag generation in codegen, it turned out to be too noisy. @banach-space expressed that these flags felt too non-standard. The tbaa tags pass can be toggled using `-mllvm -disable-fir-alias-tags=0`
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -6344,9 +6344,6 @@ defm stack_arrays : BoolOptionWithoutMarshalling<"f", "stack-arrays",
 defm loop_versioning : BoolOptionWithoutMarshalling<"f", "version-loops-for-stride",
   PosFlag<SetTrue, [], [ClangOption], "Create unit-strided versions of loops">,
    NegFlag<SetFalse, [], [ClangOption], "Do not create unit-strided loops (default)">>;
-defm alias_analysis : BoolOptionWithoutMarshalling<"f", "alias-analysis",
-  PosFlag<SetTrue, [], [], "Pass alias information on to LLVM (default when optimizing for speed)">,
-  NegFlag<SetFalse, [], [], "Do not pass alias information on to LLVM (default for unoptimized builds)">>;
 } // let Visibility = [FC1Option, FlangOption]
 
 def J : JoinedOrSeparate<["-"], "J">,
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -143,33 +143,11 @@ void Flang::addCodegenOptions(const ArgList &Args,
   if (shouldLoopVersion(Args))
     CmdArgs.push_back("-fversion-loops-for-stride");
 
-  Arg *aliasAnalysis = Args.getLastArg(options::OPT_falias_analysis,
-                                       options::OPT_fno_alias_analysis);
-  // only pass on the argument if it does not match that implied by the
-  // optimization level: so if optimization is requested, only forward
-  // -fno-alias-analysis. If optimization is not requested, only forward
-  // -falias-analysis.
-  Arg *optLevel =
-      Args.getLastArg(options::OPT_Ofast, options::OPT_O, options::OPT_O4);
-  if (aliasAnalysis) {
-    bool faliasAnalysis =
-        aliasAnalysis->getOption().matches(options::OPT_falias_analysis);
-    if (optLevel && !faliasAnalysis) {
-      CmdArgs.push_back("-fno-alias-analysis");
-    } else {
-      if (faliasAnalysis)
-        // requested alias analysis but no optimization enabled
-        CmdArgs.push_back("-falias-analysis");
-    }
-  }
-
   Args.addAllArgs(CmdArgs, {options::OPT_flang_experimental_hlfir,
                             options::OPT_flang_deprecated_no_hlfir,
                             options::OPT_flang_experimental_polymorphism,
                             options::OPT_fno_ppc_native_vec_elem_order,
-                            options::OPT_fppc_native_vec_elem_order,
-                            options::OPT_falias_analysis,
-                            options::OPT_fno_alias_analysis});
+                            options::OPT_fppc_native_vec_elem_order});
 }
 
 void Flang::addPicOptions(const ArgList &Args, ArgStringList &CmdArgs) const {
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -243,11 +243,6 @@ static void parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
     opts.LoopVersioning = 1;
 
   opts.AliasAnalysis = opts.OptimizationLevel > 0;
-  if (auto *arg =
-          args.getLastArg(clang::driver::options::OPT_falias_analysis,
-                          clang::driver::options::OPT_fno_alias_analysis))
-    opts.AliasAnalysis =
-        arg->getOption().matches(clang::driver::options::OPT_falias_analysis);
 
   for (auto *a : args.filtered(clang::driver::options::OPT_fpass_plugin_EQ))
     opts.LLVMPassPlugins.push_back(a->getValue());
diff --git a/flang/test/Driver/driver-help-hidden.f90 b/flang/test/Driver/driver-help-hidden.f90
@@ -26,7 +26,6 @@
 ! CHECK-NEXT: -D <macro>=<value>      Define <macro> to <value> (or 1 if <value> omitted)
 ! CHECK-NEXT: -emit-llvm              Use the LLVM representation for assembler and object files
 ! CHECK-NEXT: -E                      Only run the preprocessor
-! CHECK-NEXT: -falias-analysis        Pass alias information on to LLVM (default when optimizing for speed)
 ! CHECK-NEXT: -falternative-parameter-statement
 ! CHECK-NEXT:                         Enable the old style PARAMETER statement
 ! CHECK-NEXT: -fapprox-func           Allow certain math function calls to be replaced with an approximately equivalent calculation
@@ -63,7 +62,6 @@
 ! CHECK-NEXT: -flto                   Enable LTO in 'full' mode
 ! CHECK-NEXT: -fms-runtime-lib=<value>
 ! CHECK-NEXT:                         Select Windows run-time library
-! CHECK-NEXT: -fno-alias-analysis     Do not pass alias information on to LLVM (default for unoptimized builds)
 ! CHECK-NEXT: -fno-automatic          Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
 ! CHECK-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
 ! CHECK-NEXT: -fno-integrated-as      Disable the integrated assembler
diff --git a/flang/test/Driver/driver-help.f90 b/flang/test/Driver/driver-help.f90
@@ -22,7 +22,6 @@
 ! HELP-NEXT: -D <macro>=<value>      Define <macro> to <value> (or 1 if <value> omitted)
 ! HELP-NEXT: -emit-llvm              Use the LLVM representation for assembler and object files
 ! HELP-NEXT: -E                      Only run the preprocessor
-! HELP-NEXT: -falias-analysis        Pass alias information on to LLVM (default when optimizing for speed)
 ! HELP-NEXT: -falternative-parameter-statement
 ! HELP-NEXT:                         Enable the old style PARAMETER statement
 ! HELP-NEXT: -fapprox-func           Allow certain math function calls to be replaced with an approximately equivalent calculation
@@ -53,7 +52,6 @@
 ! HELP-NEXT: -flto                   Enable LTO in 'full' mode
 ! HELP-NEXT: -fms-runtime-lib=<value>
 ! HELP-NEXT:                         Select Windows run-time library
-! HELP-NEXT: -fno-alias-analysis     Do not pass alias information on to LLVM (default for unoptimized builds)
 ! HELP-NEXT: -fno-automatic          Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
 ! HELP-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
 ! HELP-NEXT: -fno-integrated-as      Disable the integrated assembler
@@ -152,7 +150,6 @@
 ! HELP-FC1-NEXT: -emit-llvm              Use the LLVM representation for assembler and object files
 ! HELP-FC1-NEXT: -emit-obj               Emit native object files
 ! HELP-FC1-NEXT: -E                      Only run the preprocessor
-! HELP-FC1-NEXT: -falias-analysis        Pass alias information on to LLVM (default when optimizing for speed)
 ! HELP-FC1-NEXT: -falternative-parameter-statement
 ! HELP-FC1-NEXT:                         Enable the old style PARAMETER statement
 ! HELP-FC1-NEXT: -fapprox-func           Allow certain math function calls to be replaced with an approximately equivalent calculation
@@ -199,7 +196,6 @@
 ! HELP-FC1-NEXT: -flogical-abbreviations Enable logical abbreviations
 ! HELP-FC1-NEXT: -flto=<value>           Set LTO mode
 ! HELP-FC1-NEXT: -flto                   Enable LTO in 'full' mode
-! HELP-FC1-NEXT: -fno-alias-analysis     Do not pass alias information on to LLVM (default for unoptimized builds)
 ! HELP-FC1-NEXT: -fno-analyzed-objects-for-unparse
 ! HELP-FC1-NEXT:                         Do not use the analyzed objects when unparsing
 ! HELP-FC1-NEXT: -fno-automatic          Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
diff --git a/flang/test/Driver/falias-analysis.f90 b/flang/test/Driver/falias-analysis.f90
@@ -1,27 +1,20 @@
-! Check that -falias-analysis and -fno-alias-analysis work as expected
+! Check that tbaa tags are enabled and disabled with optimization flags as expected
 ! 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 -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
-! RUN: %flang -c -emit-llvm -fno-alias-analysis -Ofast %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
 ! RUN: %flang -c -emit-llvm %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --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 -fc1 -emit-llvm -falias-analysis %s -o - | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
 ! RUN: %flang -fc1 -emit-llvm -O3 %s -o - | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
 ! RUN: %flang -fc1 -emit-llvm -O2 %s -o - | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
 ! RUN: %flang -fc1 -emit-llvm -O1 %s -o - | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
 
 ! RUN: %flang -fc1 -emit-llvm -O0 %s -o - | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
-! RUN: %flang -fc1 -emit-llvm -falias-analysis -fno-alias-analysis %s -o - | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
 ! RUN: %flang -fc1 -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
-! RUN: %flang -fc1 -emit-llvm -O3 -fno-alias-analysis %s -o - | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
 
 subroutine simple(a)
   integer, intent(inout) :: a(:)
