[flang] Updating drivers to create data layout before semantics (#73301)

Preliminary patch to change lowering/code generation to use
llvm::DataLayout information instead of generating "sizeof" GEP (see
https://github.com/llvm/llvm-project/issues/71507).

Fortran Semantic analysis needs to know about the target type size and
alignment to deal with common blocks, and intrinsics like
C_SIZEOF/TRANSFER. This information should be obtained from the
llvm::DataLayout so that it is consistent during the whole compilation
flow.

This change is changing flang-new and bbc drivers to:
1. Create the llvm::TargetMachine so that the data layout of the target
can be obtained before semantics.
2. Sharing bbc/flang-new set-up of the
SemanticConstext.targetCharateristics from the llvm::TargetMachine. For
now, the actual part that set-up the Fortran type size and alignment
from the llvm::DataLayout is left TODO so that this change is mostly an
NFC impacting the drivers.
3. Let the lowering bridge set-up the mlir::Module datalayout attributes
since it is doing it for the target attribute, and that allows the llvm
data layout information to be available during lowering.

For flang-new, the changes are code shuffling: the `llvm::TargetMachine`
instance is moved to `CompilerInvocation` class so that it can be used
to set-up the semantic contexts. `setMLIRDataLayout` is moved to
`flang/Optimizer/Support/DataLayout.h` (it will need to be used from
codegen pass for fir-opt target independent testing.)), and the code
setting-up semantics targetCharacteristics is moved to
`Tools/TargetSetup.h` so that it can be shared with bbc.

As a consequence, LLVM targets must be registered when running
semantics, and it is not possible to run semantics for a target that is
not registered with the -triple option (hence the power pc specific
modules can only be built if the PowerPC target is available.

1 files changed, 7 insertions, 16 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index c623969..b3f32bb 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -18,6 +18,7 @@
 #include "flang/Frontend/PreprocessorOptions.h"
 #include "flang/Frontend/TargetOptions.h"
 #include "flang/Semantics/semantics.h"
+#include "flang/Tools/TargetSetup.h"
 #include "flang/Version.inc"
 #include "clang/Basic/AllDiagnostics.h"
 #include "clang/Basic/DiagnosticDriver.h"
@@ -1347,7 +1348,8 @@ void CompilerInvocation::setFortranOpts() {
 
 std::unique_ptr<Fortran::semantics::SemanticsContext>
 CompilerInvocation::getSemanticsCtx(
-    Fortran::parser::AllCookedSources &allCookedSources) {
+    Fortran::parser::AllCookedSources &allCookedSources,
+    const llvm::TargetMachine &targetMachine) {
   auto &fortranOptions = getFortranOpts();
 
   auto semanticsContext = std::make_unique<semantics::SemanticsContext>(
@@ -1360,21 +1362,10 @@ CompilerInvocation::getSemanticsCtx(
       .set_moduleFileSuffix(getModuleFileSuffix())
       .set_underscoring(getCodeGenOpts().Underscoring);
 
-  llvm::Triple targetTriple{llvm::Triple(this->targetOpts.triple)};
-  // FIXME: Handle real(3) ?
-  if (targetTriple.getArch() != llvm::Triple::ArchType::x86_64) {
-    semanticsContext->targetCharacteristics().DisableType(
-        Fortran::common::TypeCategory::Real, /*kind=*/10);
-  }
-
-  std::string version = Fortran::common::getFlangFullVersion();
-  semanticsContext->targetCharacteristics()
-      .set_compilerOptionsString(allCompilerInvocOpts)
-      .set_compilerVersionString(version);
-
-  if (targetTriple.isPPC())
-    semanticsContext->targetCharacteristics().set_isPPC(true);
-
+  std::string compilerVersion = Fortran::common::getFlangFullVersion();
+  Fortran::tools::setUpTargetCharacteristics(
+      semanticsContext->targetCharacteristics(), targetMachine, compilerVersion,
+      allCompilerInvocOpts);
   return semanticsContext;
 }