Enable machine sinking critical edge splitting. e.g.
define double @foo(double %x, double %y, i1 %c) nounwind {
%a = fdiv double %x, 3.2
%z = select i1 %c, double %a, double %y
ret double %z
}
Was:
_foo:
divsd LCPI0_0(%rip), %xmm0
testb $1, %dil
jne LBB0_2
movaps %xmm1, %xmm0
LBB0_2:
ret
Now:
_foo:
testb $1, %dil
je LBB0_2
divsd LCPI0_0(%rip), %xmm0
ret
LBB0_2:
movaps %xmm1, %xmm0
ret
This avoids the divsd when early exit is taken.
rdar://8454886
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114372 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index fda0782..5969c0b 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -35,10 +35,7 @@
static cl::opt<bool>
SplitEdges("machine-sink-split",
cl::desc("Split critical edges during machine sinking"),
- cl::init(false), cl::Hidden);
-static cl::opt<unsigned>
-SplitLimit("split-limit",
- cl::init(~0u), cl::Hidden);
+ cl::init(true), cl::Hidden);
STATISTIC(NumSunk, "Number of machine instructions sunk");
STATISTIC(NumSplit, "Number of critical edges split");
@@ -311,7 +308,7 @@
return 0;
// Avoid breaking back edge. From == To means backedge for single BB loop.
- if (!SplitEdges || NumSplit == SplitLimit || FromBB == ToBB)
+ if (!SplitEdges || FromBB == ToBB)
return 0;
// Check for backedges of more "complex" loops.
@@ -561,8 +558,6 @@
// BreakPHIEdge is true if all the uses are in the successor MBB being
// sunken into and they are all PHI nodes. In this case, machine-sink must
// break the critical edge first.
- if (NumSplit == SplitLimit)
- return false;
MachineBasicBlock *NewSucc = SplitCriticalEdge(MI, ParentBlock,
SuccToSinkTo, BreakPHIEdge);
if (!NewSucc) {