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Hideto Ueno 96e6ce4cd3 [Attributor][MustExec] Deduce dereferenceable and nonnull attribute using MustBeExecutedContextExplorer 
Summary:
In D65186 and related patches, MustBeExecutedContextExplorer is introduced. This enables us to traverse instructions guaranteed to execute from function entry. If we can know the argument is used as `dereferenceable` or `nonnull` in these instructions, we can mark `dereferenceable` or `nonnull` in the argument definition:

1. Memory instruction (similar to D64258)
Trace memory instruction pointer operand. Currently, only inbounds GEPs are traced.
```
define i64* @f(i64* %a) {
entry:
  %add.ptr = getelementptr inbounds i64, i64* %a, i64 1
; (because of inbounds GEP we can know that %a is at least dereferenceable(16))
  store i64 1, i64* %add.ptr, align 8
  ret i64* %add.ptr ; dereferenceable 8 (because above instruction stores into it)
}
```

2. Propagation from callsite (similar to D27855)
If `deref` or `nonnull` are known in call site parameter attributes we can also say that argument also that attribute.

```
declare void @use3(i8* %x, i8* %y, i8* %z);
declare void @use3nonnull(i8* nonnull %x, i8* nonnull %y, i8* nonnull %z);

define void @parent1(i8* %a, i8* %b, i8* %c) {
  call void @use3nonnull(i8* %b, i8* %c, i8* %a)
; Above instruction is always executed so we can say that@parent1(i8* nonnnull %a, i8* nonnull %b, i8* nonnull %c)
  call void @use3(i8* %c, i8* %a, i8* %b)
  ret void
}
```

Reviewers: jdoerfert, sstefan1, spatel, reames

Reviewed By: jdoerfert

Subscribers: xbolva00, hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65402

llvm-svn: 374063
 		2019-10-08 15:25:56 +00:00
clang [clang][ifs] Clang Interface Stubs ToolChain plumbing. 2019-10-08 15:23:14 +00:00
clang-tools-extra [clangd] Disable expand auto on decltype(auto) 2019-10-08 14:03:45 +00:00
compiler-rt [sanitizer] Fix signal_trap_handler.cpp on android 2019-10-08 02:00:53 +00:00
debuginfo-tests Make nrvo-string test more robust. 2019-06-27 20:38:37 +00:00
libc Add few docs and implementation of strcpy and strcat. 2019-10-04 17:30:54 +00:00
libclc travis: Add LLVM 9 build 2019-09-27 05:58:15 +00:00
libcxx [libc++] TAKE 2: Make system libraries PRIVATE dependencies of libc++ 2019-10-08 14:53:11 +00:00
libcxxabi [libc++abi] Introduce a LIBCXXABI_LIBRARY_VERSION option 2019-10-07 19:22:04 +00:00
libunwind [libunwind] Adjust libunwind_01.pass.cpp test for ARM EHABI 2019-10-03 17:01:04 +00:00
lld [lld][Hexagon] Support PLT relocation R_HEX_B15_PCREL_X/R_HEX_B9_PCREL_X 2019-10-08 14:23:49 +00:00
lldb Tweak minidebuginfo-set-and-hit-breakpoint.test 2019-10-08 13:51:05 +00:00
llgo IR: Support parsing numeric block ids, and emit them in textual output. 2019-03-22 18:27:13 +00:00
llvm [Attributor][MustExec] Deduce dereferenceable and nonnull attribute using MustBeExecutedContextExplorer 2019-10-08 15:25:56 +00:00
openmp Don't assume Type from `readelf -d` has parentheses 2019-10-08 12:39:04 +00:00
parallel-libs Fix typos throughout the license files that somehow I and my reviewers 2019-01-21 09:52:34 +00:00
polly [Alignment][NFC] Remove StoreInst::setAlignment(unsigned) 2019-10-03 13:17:21 +00:00
pstl [pstl] Allow customizing whether per-TU insulation is provided 2019-08-13 12:49:00 +00:00
.arcconfig Update monorepo .arcconfig with new project callsign. 2019-01-31 14:34:59 +00:00
.clang-format Add .clang-tidy and .clang-format files to the toplevel of the 2019-01-29 16:43:16 +00:00
.clang-tidy Disable tidy checks with too many hits 2019-02-01 11:20:13 +00:00
.git-blame-ignore-revs Add LLDB reformatting to .git-blame-ignore-revs 2019-09-04 09:31:55 +00:00
.gitignore Add a newline at the end of the file 2019-09-04 06:33:46 +00:00
README.md
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README.md

The LLVM Compiler Infrastructure

This directory and its subdirectories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments.