[clang] [llvm] [Clang][RISCV] Move getVScaleRange logic into libLLVMFrontendDriver. NFC (PR #77327)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Luke Lau (lukel97)

<details>
<summary>Changes</summary>

In #<!-- -->77277, we would like to be able to reuse the logic for calculating the
vscale_range in Flang. This is currently in clang::TargetInfo which is quite C
specific, and given that only two targets implement getVScaleRange, it doesn't
seem worthwhile trying to shoehorn clang::TargetInfo into Flang.

This instead moves the logic into llvm/Frontend/Driver where it can be shared
by both (provided that a RISCVISAInfo is passed in: we don't want to have to
recompute it every time).


---
Full diff: https://github.com/llvm/llvm-project/pull/77327.diff


5 Files Affected:

- (modified) clang/lib/Basic/CMakeLists.txt (+1) 
- (modified) clang/lib/Basic/Targets/RISCV.cpp (+3-18) 
- (added) llvm/include/llvm/Frontend/Driver/RISCV.h (+27) 
- (modified) llvm/lib/Frontend/Driver/CMakeLists.txt (+1) 
- (added) llvm/lib/Frontend/Driver/RISCV.cpp (+37) 


``````````diff
diff --git a/clang/lib/Basic/CMakeLists.txt b/clang/lib/Basic/CMakeLists.txt
index 2e218ba7c84cca..8ab960c7212f88 100644
--- a/clang/lib/Basic/CMakeLists.txt
+++ b/clang/lib/Basic/CMakeLists.txt
@@ -2,6 +2,7 @@ set(LLVM_LINK_COMPONENTS
   Support
   TargetParser
   FrontendOpenMP
+  FrontendDriver
   )
 
 find_first_existing_vc_file("${LLVM_MAIN_SRC_DIR}" llvm_vc)
diff --git a/clang/lib/Basic/Targets/RISCV.cpp b/clang/lib/Basic/Targets/RISCV.cpp
index 6bc57a83a2d5ae..b090a9b167a202 100644
--- a/clang/lib/Basic/Targets/RISCV.cpp
+++ b/clang/lib/Basic/Targets/RISCV.cpp
@@ -15,6 +15,7 @@
 #include "clang/Basic/MacroBuilder.h"
 #include "clang/Basic/TargetBuiltins.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/Frontend/Driver/RISCV.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TargetParser/RISCVTargetParser.h"
 #include <optional>
@@ -321,24 +322,8 @@ bool RISCVTargetInfo::initFeatureMap(
 
 std::optional<std::pair<unsigned, unsigned>>
 RISCVTargetInfo::getVScaleRange(const LangOptions &LangOpts) const {
-  // RISCV::RVVBitsPerBlock is 64.
-  unsigned VScaleMin = ISAInfo->getMinVLen() / llvm::RISCV::RVVBitsPerBlock;
-
-  if (LangOpts.VScaleMin || LangOpts.VScaleMax) {
-    // Treat Zvl*b as a lower bound on vscale.
-    VScaleMin = std::max(VScaleMin, LangOpts.VScaleMin);
-    unsigned VScaleMax = LangOpts.VScaleMax;
-    if (VScaleMax != 0 && VScaleMax < VScaleMin)
-      VScaleMax = VScaleMin;
-    return std::pair<unsigned, unsigned>(VScaleMin ? VScaleMin : 1, VScaleMax);
-  }
-
-  if (VScaleMin > 0) {
-    unsigned VScaleMax = ISAInfo->getMaxVLen() / llvm::RISCV::RVVBitsPerBlock;
-    return std::make_pair(VScaleMin, VScaleMax);
-  }
-
-  return std::nullopt;
+  return llvm::driver::riscv::getVScaleRange(*ISAInfo, LangOpts.VScaleMin,
+                                             LangOpts.VScaleMax);
 }
 
 /// Return true if has this feature, need to sync with handleTargetFeatures.
diff --git a/llvm/include/llvm/Frontend/Driver/RISCV.h b/llvm/include/llvm/Frontend/Driver/RISCV.h
new file mode 100644
index 00000000000000..1f81f089087b51
--- /dev/null
+++ b/llvm/include/llvm/Frontend/Driver/RISCV.h
@@ -0,0 +1,27 @@
+//===--- RISCV.h ------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines RISC-V frontend logic common to clang and flang
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_FRONTEND_DRIVER_RISCV_H
+#define LLVM_FRONTEND_DRIVER_RISCV_H
+
+#include "llvm/Support/RISCVISAInfo.h"
+#include <optional>
+
+namespace llvm::driver::riscv {
+
+std::optional<std::pair<unsigned, unsigned>>
+getVScaleRange(const RISCVISAInfo &ISAInfo, unsigned ExplicitMin,
+               unsigned ExplicitMax);
+
+} // namespace llvm::driver::riscv
+
+#endif
diff --git a/llvm/lib/Frontend/Driver/CMakeLists.txt b/llvm/lib/Frontend/Driver/CMakeLists.txt
index 23de4994a300d8..ac0bc27a248a36 100644
--- a/llvm/lib/Frontend/Driver/CMakeLists.txt
+++ b/llvm/lib/Frontend/Driver/CMakeLists.txt
@@ -1,5 +1,6 @@
 add_llvm_component_library(LLVMFrontendDriver
   CodeGenOptions.cpp
+  RISCV.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/Frontend/Driver
diff --git a/llvm/lib/Frontend/Driver/RISCV.cpp b/llvm/lib/Frontend/Driver/RISCV.cpp
new file mode 100644
index 00000000000000..dfe07fb74550fd
--- /dev/null
+++ b/llvm/lib/Frontend/Driver/RISCV.cpp
@@ -0,0 +1,37 @@
+//===--- RISCV.cpp - Shared RISC-V frontend logic -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Frontend/Driver/RISCV.h"
+#include "llvm/TargetParser/RISCVTargetParser.h"
+
+namespace llvm::driver::riscv {
+
+std::optional<std::pair<unsigned, unsigned>>
+getVScaleRange(const RISCVISAInfo &ISAInfo, unsigned ExplicitMin,
+               unsigned ExplicitMax) {
+  // RISCV::RVVBitsPerBlock is 64.
+  unsigned VScaleMin = ISAInfo.getMinVLen() / RISCV::RVVBitsPerBlock;
+
+  if (ExplicitMin || ExplicitMax) {
+    // Treat Zvl*b as a lower bound on vscale.
+    VScaleMin = std::max(VScaleMin, ExplicitMin);
+    unsigned VScaleMax = ExplicitMax;
+    if (VScaleMax != 0 && VScaleMax < VScaleMin)
+      VScaleMax = VScaleMin;
+    return std::pair<unsigned, unsigned>(VScaleMin ? VScaleMin : 1, VScaleMax);
+  }
+
+  if (VScaleMin > 0) {
+    unsigned VScaleMax = ISAInfo.getMaxVLen() / RISCV::RVVBitsPerBlock;
+    return std::make_pair(VScaleMin, VScaleMax);
+  }
+
+  return std::nullopt;
+}
+
+} // namespace llvm::driver::riscv

``````````

</details>


https://github.com/llvm/llvm-project/pull/77327