llvm-project/clang
Sander de Smalen 0f7bbbc481 Always emit error for wrong interfaces to scalable vectors, unless cmdline flag is passed.
In order to bring up scalable vector support in LLVM incrementally,
we introduced behaviour to emit a warning, instead of an error, when
asking the wrong question of a scalable vector, like asking for the
fixed number of elements.

This patch puts that behaviour under a flag. The default behaviour is
that the compiler will always error, which means that all LLVM unit
tests and regression tests will now fail when a code-path is taken that
still uses the wrong interface.

The behaviour to demote an error to a warning can be individually enabled
for tools that want to support experimental use of scalable vectors.
This patch enables that behaviour when driving compilation from Clang.
This means that for users who want to try out scalable-vector support,
fixed-width codegen support, or build user-code with scalable vector
intrinsics, Clang will not crash and burn when the compiler encounters
such a case.

This allows us to do away with the following pattern in many of the SVE tests:
  RUN: .... 2>%t
  RUN: cat %t | FileCheck --check-prefix=WARN
  WARN-NOT: warning: ...

The behaviour to emit warnings is only temporary and we expect this flag
to be removed in the future when scalable vector support is more stable.

This patch also has fixes the following tests:
 unittests:
   ScalableVectorMVTsTest.SizeQueries
   SelectionDAGAddressAnalysisTest.unknownSizeFrameObjects
   AArch64SelectionDAGTest.computeKnownBitsSVE_ZERO_EXTEND_VECTOR_INREG

 regression tests:
   Transforms/InstCombine/vscale_gep.ll

Reviewed By: paulwalker-arm, ctetreau

Differential Revision: https://reviews.llvm.org/D98856
2021-04-02 10:55:22 +01:00
..
INPUTS
bindings [NFC] Don't run python binding tests with sanitizers 2020-10-29 23:48:08 -07:00
cmake [CMake][Fuchsia] Include llvm-lipo 2021-03-24 14:21:40 -07:00
docs [OpenCL][Docs] Update links to the C++ for OpenCL documentation 2021-04-01 20:38:24 +01:00
examples Refactoring the attribute plugin example to fit the new API 2020-12-21 08:24:09 -05:00
include [clang-cl] [Sema] Do not prefer integral conversion over floating-to-integral for MS compatibility 19.28 and higher. 2021-04-02 08:58:22 +02:00
lib Always emit error for wrong interfaces to scalable vectors, unless cmdline flag is passed. 2021-04-02 10:55:22 +01:00
runtime [compiler-rt] Fix stale incremental builds when using `LLVM_BUILD_EXTERNAL_COMPILER_RT=ON`. 2021-03-10 09:42:24 -08:00
test [clang-cl] [Sema] Do not prefer integral conversion over floating-to-integral for MS compatibility 19.28 and higher. 2021-04-02 08:58:22 +02:00
tools [OPENMP51]Initial support for the dispatch directive. 2021-03-30 14:12:53 -07:00
unittests [clang][ItaniumMangle] Check SizeExpr for DependentSizedArrayType 2021-04-02 15:31:20 +08:00
utils [www] List both the regular and expanded form of %diff in the 2021-03-30 17:25:01 -07:00
www [C++2b] Support size_t literals 2021-03-31 13:36:23 +00:00
.clang-format
.clang-tidy
.gitignore
CMakeLists.txt [clang][cli] Round-trip cc1 arguments in assert builds 2021-03-27 17:24:03 +01:00
CODE_OWNERS.TXT
INSTALL.txt
LICENSE.TXT
ModuleInfo.txt
NOTES.txt
README.txt

README.txt

//===----------------------------------------------------------------------===//
// C Language Family Front-end
//===----------------------------------------------------------------------===//

Welcome to Clang.  This is a compiler front-end for the C family of languages
(C, C++, Objective-C, and Objective-C++) which is built as part of the LLVM
compiler infrastructure project.

Unlike many other compiler frontends, Clang is useful for a number of things
beyond just compiling code: we intend for Clang to be host to a number of
different source-level tools.  One example of this is the Clang Static Analyzer.

If you're interested in more (including how to build Clang) it is best to read
the relevant web sites.  Here are some pointers:

Information on Clang:             http://clang.llvm.org/
Building and using Clang:         http://clang.llvm.org/get_started.html
Clang Static Analyzer:            http://clang-analyzer.llvm.org/
Information on the LLVM project:  http://llvm.org/

If you have questions or comments about Clang, a great place to discuss them is
on the Clang development mailing list:
  http://lists.llvm.org/mailman/listinfo/cfe-dev

If you find a bug in Clang, please file it in the LLVM bug tracker:
  http://llvm.org/bugs/