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| author | Peter Smith <peter.smith@linaro.org> | 2018-10-08 09:38:28 +0000 |
|---|---|---|
| committer | Peter Smith <peter.smith@linaro.org> | 2018-10-08 09:38:28 +0000 |
| commit | 6f36cd4d76c65796b695df1a34c501ac3aa05229 (patch) | |
| tree | f7c9bbd09bc10453301a0261273f23a0a7605d17 /llvm/lib/Transforms | |
| parent | 9ecdac8ee0884b02e3aff87bf61472c207824ef4 (diff) | |
| download | bcm5719-llvm-6f36cd4d76c65796b695df1a34c501ac3aa05229.tar.gz bcm5719-llvm-6f36cd4d76c65796b695df1a34c501ac3aa05229.zip | |
[ARM] Account for implicit IT when calculating inline asm size
When deciding if it is safe to optimize a conditional branch to a CBZ or
CBNZ the offsets of the BasicBlocks from the start of the function are
estimated. For inline assembly the generic getInlineAsmLength() function is
used to get a worst case estimate of the inline assembly by multiplying the
number of instructions by the max instruction size of 4 bytes. This
unfortunately doesn't take into account the generation of Thumb implicit IT
instructions. In edge cases such as when all the instructions in the block
are 4-bytes in size and there is an implicit IT then the size is
underestimated. This can cause an out of range CBZ or CBNZ to be generated.
The patch takes a conservative approach and assumes that every instruction
in the inline assembly block may have an implicit IT.
Fixes pr31805
Differential Revision: https://reviews.llvm.org/D52834
llvm-svn: 343960
Diffstat (limited to 'llvm/lib/Transforms')
0 files changed, 0 insertions, 0 deletions
