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| author | Michael Zolotukhin <mzolotukhin@apple.com> | 2017-12-21 01:22:13 +0000 |
|---|---|---|
| committer | Michael Zolotukhin <mzolotukhin@apple.com> | 2017-12-21 01:22:13 +0000 |
| commit | ad371e0caa6203e7e10aac9ef5aeac2a8618c8d4 (patch) | |
| tree | 449b45de65d276cc8ebca0c95325a237f3115c9f /llvm/test/CodeGen/ARM/avoid-cpsr-rmw.ll | |
| parent | 5c73c49c9fccd3fd3fa69269e0eb16ee59ff0f78 (diff) | |
| download | bcm5719-llvm-ad371e0caa6203e7e10aac9ef5aeac2a8618c8d4.tar.gz bcm5719-llvm-ad371e0caa6203e7e10aac9ef5aeac2a8618c8d4.zip | |
[SimplifyCFG] Avoid quadratic on a predecessors number behavior in instruction sinking.
If a block has N predecessors, then the current algorithm will try to
sink common code to this block N times (whenever we visit a
predecessor). Every attempt to sink the common code includes going
through all predecessors, so the complexity of the algorithm becomes
O(N^2).
With this patch we try to sink common code only when we visit the block
itself. With this, the complexity goes down to O(N).
As a side effect, the moment the code is sunk is slightly different than
before (the order of simplifications has been changed), that's why I had
to adjust two tests (note that neither of the tests is supposed to test
SimplifyCFG):
* test/CodeGen/AArch64/arm64-jumptable.ll - changes in this test mimic
the changes that previous implementation of SimplifyCFG would do.
* test/CodeGen/ARM/avoid-cpsr-rmw.ll - in this test I disabled common
code sinking by a command line flag.
llvm-svn: 321236
Diffstat (limited to 'llvm/test/CodeGen/ARM/avoid-cpsr-rmw.ll')
| -rw-r--r-- | llvm/test/CodeGen/ARM/avoid-cpsr-rmw.ll | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/llvm/test/CodeGen/ARM/avoid-cpsr-rmw.ll b/llvm/test/CodeGen/ARM/avoid-cpsr-rmw.ll index 78d3ebf371a..9373c5d4421 100644 --- a/llvm/test/CodeGen/ARM/avoid-cpsr-rmw.ll +++ b/llvm/test/CodeGen/ARM/avoid-cpsr-rmw.ll @@ -1,5 +1,5 @@ -; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mcpu=cortex-a9 | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-CORTEX -; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mcpu=swift | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-SWIFT +; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mcpu=cortex-a9 -simplifycfg-sink-common=false | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-CORTEX +; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mcpu=swift -simplifycfg-sink-common=false | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-SWIFT ; Avoid some 's' 16-bit instruction which partially update CPSR (and add false ; dependency) when it isn't dependent on last CPSR defining instruction. ; rdar://8928208 |
