Commit Graph

2 Commits

Author SHA1 Message Date
Tom Stellard 92339e888f AMDGPU/SI: Fix threshold calculation for branching when exec is zero
Summary:
When control flow is implemented using the exec mask, the compiler will
insert branch instructions to skip over the masked section when exec is
zero if the section contains more than a certain number of instructions.

The previous code would only count instructions in successor blocks,
and this patch modifies the code to start counting instructions in all
blocks between the start and end of the branch.

Reviewers: nhaehnle, arsenm

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D18282

llvm-svn: 263969
2016-03-21 18:56:58 +00:00
Nicolai Haehnle ef160de3e5 AMDGPU: Prevent uniform loops from becoming infinite
Summary:
Uniform loops where the branch leaving the loop is predicated on VCCNZ
must be skipped if EXEC = 0, otherwise they will be infinite.

Reviewers: tstellarAMD, arsenm

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D18137

llvm-svn: 263658
2016-03-16 20:14:33 +00:00