Revert "[IR] Remove options to make scalable TypeSize access a warning (#156336)"

This reverts commit 8f59a94.

Failed on clang-aarch64-sve-vls-2stage, which still uses the option.

Author: nikic

llvm/CMakeLists.txt

@@ -706,6 +706,18 @@ endif()
 
 option(LLVM_ENABLE_EXPENSIVE_CHECKS "Enable expensive checks" OFF)
 
+# While adding scalable vector support to LLVM, we temporarily want to
+# allow an implicit conversion of TypeSize to uint64_t, and to allow
+# code to get the fixed number of elements from a possibly scalable vector.
+# This CMake flag enables a more strict mode where it asserts that the type
+# is not a scalable vector type.
+#
+# Enabling this flag makes it easier to find cases where the compiler makes
+# assumptions on the size being 'fixed size', when building tests for
+# SVE/SVE2 or other scalable vector architectures.
+option(LLVM_ENABLE_STRICT_FIXED_SIZE_VECTORS
+       "Enable assertions that type is not scalable in implicit conversion from TypeSize to uint64_t and calls to getNumElements" OFF)
+
 set(LLVM_ABI_BREAKING_CHECKS "WITH_ASSERTS" CACHE STRING
   "Enable abi-breaking checks.  Can be WITH_ASSERTS, FORCE_ON or FORCE_OFF.")
 

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -201,6 +201,10 @@ if (LLVM_USES_LIBSTDCXX)
   endif()
 endif()
 
+if (LLVM_ENABLE_STRICT_FIXED_SIZE_VECTORS)
+  add_compile_definitions(STRICT_FIXED_SIZE_VECTORS)
+endif()
+
 string(TOUPPER "${LLVM_ABI_BREAKING_CHECKS}" uppercase_LLVM_ABI_BREAKING_CHECKS)
 
 if( uppercase_LLVM_ABI_BREAKING_CHECKS STREQUAL "WITH_ASSERTS" )

llvm/include/llvm/CodeGen/ValueTypes.h

@@ -332,7 +332,7 @@ namespace llvm {
       assert(isVector() && "Invalid vector type!");
 
       if (isScalableVector())
-        llvm::reportFatalInternalError(
+        llvm::reportInvalidSizeRequest(
             "Possible incorrect use of EVT::getVectorNumElements() for "
             "scalable vector. Scalable flag may be dropped, use "
             "EVT::getVectorElementCount() instead");

llvm/include/llvm/CodeGenTypes/LowLevelType.h

@@ -159,7 +159,7 @@ class LLT {
   /// vector types.
   constexpr uint16_t getNumElements() const {
     if (isScalable())
-      llvm::reportFatalInternalError(
+      llvm::reportInvalidSizeRequest(
           "Possible incorrect use of LLT::getNumElements() for "
           "scalable vector. Scalable flag may be dropped, use "
           "LLT::getElementCount() instead");

llvm/include/llvm/CodeGenTypes/MachineValueType.h

@@ -294,7 +294,7 @@ namespace llvm {
 
     unsigned getVectorNumElements() const {
       if (isScalableVector())
-        llvm::reportFatalInternalError(
+        llvm::reportInvalidSizeRequest(
             "Possible incorrect use of MVT::getVectorNumElements() for "
             "scalable vector. Scalable flag may be dropped, use "
             "MVT::getVectorElementCount() instead");

llvm/include/llvm/Support/TypeSize.h

@@ -26,6 +26,10 @@
 
 namespace llvm {
 
+/// Reports a diagnostic message to indicate an invalid size request has been
+/// done on a scalable vector. This function may not return.
+LLVM_ABI void reportInvalidSizeRequest(const char *Msg);
+
 /// StackOffset holds a fixed and a scalable offset in bytes.
 class StackOffset {
   int64_t Fixed = 0;

llvm/lib/Support/CommandLine.cpp

@@ -2671,6 +2671,7 @@ static void initCommonOptions() {
   initSignalsOptions();
   initStatisticOptions();
   initTimerOptions();
+  initTypeSizeOptions();
   initWithColorOptions();
   initDebugOptions();
   initRandomSeedOptions();

llvm/lib/Support/DebugOptions.h

@@ -24,6 +24,7 @@ void initGraphWriterOptions();
 void initSignalsOptions();
 void initStatisticOptions();
 void initTimerOptions();
+void initTypeSizeOptions();
 void initWithColorOptions();
 void initDebugOptions();
 void initRandomSeedOptions();

llvm/lib/Support/TypeSize.cpp

@@ -7,13 +7,49 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/TypeSize.h"
-#include "llvm/Support/Error.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/WithColor.h"
+
+#include "DebugOptions.h"
 
 using namespace llvm;
 
+#ifndef STRICT_FIXED_SIZE_VECTORS
+namespace {
+struct CreateScalableErrorAsWarning {
+  /// The ScalableErrorAsWarning is a temporary measure to suppress errors from
+  /// using the wrong interface on a scalable vector.
+  static void *call() {
+    return new cl::opt<bool>(
+        "treat-scalable-fixed-error-as-warning", cl::Hidden,
+        cl::desc(
+            "Treat issues where a fixed-width property is requested from a "
+            "scalable type as a warning, instead of an error"));
+  }
+};
+} // namespace
+static ManagedStatic<cl::opt<bool>, CreateScalableErrorAsWarning>
+    ScalableErrorAsWarning;
+void llvm::initTypeSizeOptions() { *ScalableErrorAsWarning; }
+#else
+void llvm::initTypeSizeOptions() {}
+#endif
+
+void llvm::reportInvalidSizeRequest(const char *Msg) {
+#ifndef STRICT_FIXED_SIZE_VECTORS
+  if (*ScalableErrorAsWarning) {
+    WithColor::warning() << "Invalid size request on a scalable vector; " << Msg
+                         << "\n";
+    return;
+  }
+#endif
+  report_fatal_error("Invalid size request on a scalable vector.");
+}
+
 TypeSize::operator TypeSize::ScalarTy() const {
   if (isScalable()) {
-    reportFatalInternalError(
+    reportInvalidSizeRequest(
         "Cannot implicitly convert a scalable size to a fixed-width size in "
         "`TypeSize::operator ScalarTy()`");
     return getKnownMinValue();

llvm/test/CodeGen/AArch64/sms-order-physreg-deps.mir

@@ -1,4 +1,4 @@
-# RUN: llc --verify-machineinstrs -mtriple=aarch64 -o - %s -mcpu=a64fx -aarch64-enable-pipeliner -pipeliner-max-mii=100 -pipeliner-enable-copytophi=0 -debug-only=pipeliner -run-pass=pipeliner 2>&1 | FileCheck %s
+# RUN: llc --verify-machineinstrs -mtriple=aarch64 -o - %s -mcpu=a64fx -aarch64-enable-pipeliner -pipeliner-max-mii=100 -pipeliner-enable-copytophi=0 -debug-only=pipeliner -run-pass=pipeliner -treat-scalable-fixed-error-as-warning 2>&1 | FileCheck %s
 
 # REQUIRES: asserts