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Sanjay Patel bfee5a9b42 [x86] fix uses check in broadcast transform (PR38949)
https://bugs.llvm.org/show_bug.cgi?id=38949

It's not clear to me that we even need a one-use check in this fold.
Ie, 2 independent loads might be better than a load+dependent shuffle.

Note that the existing re-use tests are not affected. We actually do form a
broadcast node in those tests now because there's no extra use of the 
insert_subvector node in those cases. But something later in isel pattern 
matching decides that it is not worth using a broadcast for the full load in 
those tests:

Legalized selection DAG: %bb.0 'test_broadcast_2f64_4f64_reuse:'
  t7: v2f64,ch = load<(load 16 from %ir.p0)> t0, t2, undef:i64
      t4: i64,ch = CopyFromReg t0, Register:i64 %1
    t10: ch = store<(store 16 into %ir.p1)> t7:1, t7, t4, undef:i64
      t18: v4f64 = insert_subvector undef:v4f64, t7, Constant:i64<0>
    t20: v4f64 = insert_subvector t18, t7, Constant:i64<2>

Becomes:
  t7: v2f64,ch = load<(load 16 from %ir.p0)> t0, t2, undef:i64
      t4: i64,ch = CopyFromReg t0, Register:i64 %1
    t10: ch = store<(store 16 into %ir.p1)> t7:1, t7, t4, undef:i64
    t21: v4f64 = X86ISD::SUBV_BROADCAST t7

ISEL: Starting selection on root node: t21: v4f64 = X86ISD::SUBV_BROADCAST t7
...
  Created node: t27: v4f64 = INSERT_SUBREG IMPLICIT_DEF:v4f64, t7, TargetConstant:i32<7>
  Morphed node: t21: v4f64 = VINSERTF128rr t27, t7, TargetConstant:i8<1>

llvm-svn: 342347
2018-09-16 15:41:56 +00:00
clang [NFC] cosmetic tweaks to ExprMutationAnalyzer to be more consistent 2018-09-15 21:38:18 +00:00
clang-tools-extra Mark index-tools.test as REQUIRES: shell so that it does not run with the internal lit shell which does not support "if" 2018-09-14 20:51:07 +00:00
compiler-rt [XRay] Remove the unused variable 2018-09-15 06:25:17 +00:00
debuginfo-tests Revert "(Retry) Add a basic integration test for C++ smart pointers" 2018-08-20 19:53:33 +00:00
libclc configure: Rework support for gfx9+ devices that were added post LLVM 3.9 2018-09-15 22:02:01 +00:00
libcxx Mark LWG#3102 as complete. No code changes, but I updated a test or two 2018-09-13 02:23:52 +00:00
libcxxabi Merge Demangle change in r342330 to libcxxabi. 2018-09-15 18:25:49 +00:00
libunwind [CMake] Don't use -rtlib=compiler-rt with -nodefaultlibs. 2018-09-04 20:57:50 +00:00
lld [ELF] Use llvm::toLower instead of libc call tolower 2018-09-15 23:59:13 +00:00
lldb [lldb-mi] Correct regex in the symbol-list-lines test 2018-09-15 17:05:20 +00:00
llgo Update copyright year to 2018. 2018-06-18 12:22:17 +00:00
llvm [x86] fix uses check in broadcast transform (PR38949) 2018-09-16 15:41:56 +00:00
openmp [OPENMP]Increment iterator when the loop is continued. 2018-09-11 17:16:26 +00:00
parallel-libs Update copyright year to 2018. 2018-06-18 12:22:17 +00:00
polly [ScopDetection] Use addUnknown for calls in the AliasSetTracker. 2018-09-11 23:48:14 +00:00
README.md

README.md

Low Level Virtual Machine (LLVM)

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