6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-02 07:11:49 +00:00
Code Issues Projects Releases Wiki Activity
9a97f23f2f
llvm-6502/test
History
Arnold Schwaighofer dd8c386432 SimplifyCFG: Don't convert phis into selects if we could remove undef behavior 
instead

We used to transform this:

  define void @test6(i1 %cond, i8* %ptr) {
  entry:
    br i1 %cond, label %bb1, label %bb2

  bb1:
    br label %bb2

  bb2:
    %ptr.2 = phi i8* [ %ptr, %entry ], [ null, %bb1 ]
    store i8 2, i8* %ptr.2, align 8
    ret void
  }

into this:

  define void @test6(i1 %cond, i8* %ptr) {
    %ptr.2 = select i1 %cond, i8* null, i8* %ptr
    store i8 2, i8* %ptr.2, align 8
    ret void
  }

because the simplifycfg transformation into selects would happen to happen
before the simplifycfg transformation that removes unreachable control flow
(We have 'unreachable control flow' due to the store to null which is undefined
behavior).

The existing transformation that removes unreachable control flow in simplifycfg
is:

  /// If BB has an incoming value that will always trigger undefined behavior
  /// (eg. null pointer dereference), remove the branch leading here.
  static bool removeUndefIntroducingPredecessor(BasicBlock *BB)

Now we generate:

  define void @test6(i1 %cond, i8* %ptr) {
    store i8 2, i8* %ptr.2, align 8
    ret void
  }

I did not see any impact on the test-suite + externals.

rdar://18596215

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219462 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-10 01:27:02 +00:00
..
Analysis Revert "[BasicAA] Revert "Revert r218714 - Make better use of zext and sign information."" 2014-10-09 19:48:12 +00:00
Assembler Revert "Revert "DI: Fold constant arguments into a single MDString"" 2014-10-03 20:01:09 +00:00
Bindings Revert "Revert "DI: Fold constant arguments into a single MDString"" 2014-10-03 20:01:09 +00:00
Bitcode Revert "Revert "DI: Fold constant arguments into a single MDString"" 2014-10-03 20:01:09 +00:00
BugPoint Revert "Revert "DI: Fold constant arguments into a single MDString"" 2014-10-03 20:01:09 +00:00
CodeGen Improve sqrt estimate algorithm (fast-math) 2014-10-09 21:26:35 +00:00
DebugInfo Fix COFF section index relocation should be 16 bits, not 32 2014-10-08 18:01:49 +00:00
ExecutionEngine [mips] Remove XFAIL from two XPASS'ing tests on the llvm-mips-linux builder 2014-10-03 08:49:44 +00:00
Feature Revert "Revert "DI: Fold constant arguments into a single MDString"" 2014-10-03 20:01:09 +00:00
FileCheck
Instrumentation DebugInfo+DFSan: Ensure that debug info references to llvm::Functions remain pointing to the underlying function when wrappers are created 2014-10-07 22:59:46 +00:00
Integer
JitListener Revert "Revert "DI: Fold constant arguments into a single MDString"" 2014-10-03 20:01:09 +00:00
Linker [dwarfdump] Print the name for referenced specification of abstract_origin DIEs. 2014-10-06 03:36:31 +00:00
LTO
MC [PPC64] VSX indexed-form loads use wrong instruction format 2014-10-09 17:51:35 +00:00
Object obj2yaml, COFF: Handle long section names 2014-10-10 00:17:57 +00:00
Other
TableGen
tools llvm-readobj: add test for r219228 2014-10-08 02:06:11 +00:00
Transforms SimplifyCFG: Don't convert phis into selects if we could remove undef behavior 2014-10-10 01:27:02 +00:00
Unit
Verifier
YAMLParser
.clang-format
CMakeLists.txt
lit.cfg llvm/test/lit.cfg: Suppress dwarf stuff for targeting x86_64-mingw32 while investigating since r219108. 2014-10-06 23:29:06 +00:00
lit.site.cfg.in
Makefile
Makefile.tests
TestRunner.sh