Commit Graph

4 Commits

Author SHA1 Message Date
Evan Cheng 2f2435d026 Last round of fixes for movw + movt global address codegen.
1. Fixed ARM pc adjustment.
2. Fixed dynamic-no-pic codegen
3. CSE of pc-relative load of global addresses.

It's now enabled by default for Darwin.

llvm-svn: 123991
2011-01-21 18:55:51 +00:00
Evan Cheng 028ccbfcbf Don't be overly aggressive with CSE of "ldr constantpool". If it's a pc-relative
value, the "add pc" must be CSE'ed at the same time. We could follow the same
approach as T2 by adding pseudo instructions that combine the ldr + "add pc".
But the better approach is to use movw + movt (which I will enable soon), so
I'll leave this as a TODO.

llvm-svn: 123949
2011-01-20 23:55:07 +00:00
Evan Cheng f2e914be15 Add test.
llvm-svn: 123906
2011-01-20 08:38:21 +00:00
Evan Cheng b8b0ad80a8 Sorry, several patches in one.
TargetInstrInfo:
Change produceSameValue() to take MachineRegisterInfo as an optional argument.
When in SSA form, targets can use it to make more aggressive equality analysis.

Machine LICM:
1. Eliminate isLoadFromConstantMemory, use MI.isInvariantLoad instead.
2. Fix a bug which prevent CSE of instructions which are not re-materializable.
3. Use improved form of produceSameValue.

ARM:
1. Teach ARM produceSameValue to look pass some PIC labels.
2. Look for operands from different loads of different constant pool entries
   which have same values.
3. Re-implement PIC GA materialization using movw + movt. Combine the pair with
   a "add pc" or "ldr [pc]" to form pseudo instructions. This makes it possible
   to re-materialize the instruction, allow machine LICM to hoist the set of
   instructions out of the loop and make it possible to CSE them. It's a bit
   hacky, but it significantly improve code quality.
4. Some minor bug fixes as well.

With the fixes, using movw + movt to materialize GAs significantly outperform the
load from constantpool method. 186.crafty and 255.vortex improved > 20%, 254.gap
and 176.gcc ~10%.

llvm-svn: 123905
2011-01-20 08:34:58 +00:00