llvm-6502/test
Hal Finkel 36e1825e68 Add CR-bit tracking to the PowerPC backend for i1 values
This change enables tracking i1 values in the PowerPC backend using the
condition register bits. These bits can be treated on PowerPC as separate
registers; individual bit operations (and, or, xor, etc.) are supported.
Tracking booleans in CR bits has several advantages:

 - Reduction in register pressure (because we no longer need GPRs to store
   boolean values).

 - Logical operations on booleans can be handled more efficiently; we used to
   have to move all results from comparisons into GPRs, perform promoted
   logical operations in GPRs, and then move the result back into condition
   register bits to be used by conditional branches. This can be very
   inefficient, because the throughput of these CR <-> GPR moves have high
   latency and low throughput (especially when other associated instructions
   are accounted for).

 - On the POWER7 and similar cores, we can increase total throughput by using
   the CR bits. CR bit operations have a dedicated functional unit.

Most of this is more-or-less mechanical: Adjustments were needed in the
calling-convention code, support was added for spilling/restoring individual
condition-register bits, and conditional branch instruction definitions taking
specific CR bits were added (plus patterns and code for generating bit-level
operations).

This is enabled by default when running at -O2 and higher. For -O0 and -O1,
where the ability to debug is more important, this feature is disabled by
default. Individual CR bits do not have assigned DWARF register numbers,
and storing values in CR bits makes them invisible to the debugger.

It is critical, however, that we don't move i1 values that have been promoted
to larger values (such as those passed as function arguments) into bit
registers only to quickly turn around and move the values back into GPRs (such
as happens when values are returned by functions). A pair of target-specific
DAG combines are added to remove the trunc/extends in:
  trunc(binary-ops(binary-ops(zext(x), zext(y)), ...)
and:
  zext(binary-ops(binary-ops(trunc(x), trunc(y)), ...)
In short, we only want to use CR bits where some of the i1 values come from
comparisons or are used by conditional branches or selects. To put it another
way, if we can do the entire i1 computation in GPRs, then we probably should
(on the POWER7, the GPR-operation throughput is higher, and for all cores, the
CR <-> GPR moves are expensive).

POWER7 test-suite performance results (from 10 runs in each configuration):

SingleSource/Benchmarks/Misc/mandel-2: 35% speedup
MultiSource/Benchmarks/Prolangs-C++/city/city: 21% speedup
MultiSource/Benchmarks/MiBench/automotive-susan: 23% speedup
SingleSource/Benchmarks/CoyoteBench/huffbench: 13% speedup
SingleSource/Benchmarks/Misc-C++/Large/sphereflake: 13% speedup
SingleSource/Benchmarks/Misc-C++/mandel-text: 10% speedup

SingleSource/Benchmarks/Misc-C++-EH/spirit: 10% slowdown
MultiSource/Applications/lemon/lemon: 8% slowdown

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202451 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-28 00:27:01 +00:00
..
Analysis add -da-delinearize runs and checks to MIV testcases 2014-02-21 18:15:18 +00:00
Assembler Bug 18228 - Fix accepting bitcasts between vectors of pointers with a 2014-01-22 19:21:33 +00:00
Bindings Don't try to set a dummy DataLayout. It is parsed now. 2014-02-25 20:41:28 +00:00
Bitcode Ensure bitcode encoding of instructions and their operands stays stable. 2014-02-26 12:06:36 +00:00
BugPoint
CodeGen Add CR-bit tracking to the PowerPC backend for i1 values 2014-02-28 00:27:01 +00:00
DebugInfo Debug info: Remove ARMAsmPrinter::EmitDwarfRegOp(). AsmPrinter can now 2014-02-27 17:56:08 +00:00
ExecutionEngine Ignore old JIT tests in AARch64 - CMake style 2014-02-25 09:31:00 +00:00
Feature Disable most IR-level transform passes on functions marked 'optnone'. 2014-02-06 00:07:05 +00:00
FileCheck
Instrumentation [asan] remove test that should have been removed in r202033 2014-02-24 13:44:24 +00:00
Integer
JitListener
Linker Revert "Use count 0." 2014-02-27 03:10:10 +00:00
LTO Add back r201608, r201622, r201624 and r201625 2014-02-19 17:23:20 +00:00
MC Fix typos 2014-02-25 04:21:15 +00:00
Object Add a SymbolicFile interface between Binary and ObjectFile. 2014-02-21 20:10:59 +00:00
Other [PM] Wire up the Verifier for the new pass manager and connect it to the 2014-01-20 11:34:08 +00:00
TableGen [TableGen] Correctly generate implicit anonymous prototype defs in multiclasses 2014-01-02 20:47:09 +00:00
tools Relax COFF string table check 2014-02-26 19:51:44 +00:00
Transforms Add a debug info code generation level to the compile unit metadata 2014-02-27 01:24:56 +00:00
Unit
Verifier [PM] Make the verifier work independently of any pass manager. 2014-01-19 02:22:18 +00:00
YAMLParser
.clang-format
CMakeLists.txt [CMake] Remove dependency on non-existing profile_rt-shared. Patch by Brad King. 2014-02-24 15:07:06 +00:00
lit.cfg PGO: llvm-profdata: tool for merging profiles 2014-02-17 23:22:49 +00:00
lit.site.cfg.in Eliminate inappropriate use of FindProgramByName() from lli 2014-01-22 21:52:35 +00:00
Makefile Eliminate inappropriate use of FindProgramByName() from lli 2014-01-22 21:52:35 +00:00
Makefile.tests
TestRunner.sh