Add a subtarget hook for reporting the misprediction penalty. Use this to provide more precise
cost modeling for if-conversion. Now if only we had a way to estimate the misprediction probability.
Adjsut CodeGen/ARM/ifcvt10.ll. The pipeline on Cortex-A8 is long enough that it is still profitable
to predicate an ldm, but the shorter pipeline on Cortex-A9 makes it unprofitable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114995 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMSubtarget.cpp b/lib/Target/ARM/ARMSubtarget.cpp
index 6ecb512..65bb85f 100644
--- a/lib/Target/ARM/ARMSubtarget.cpp
+++ b/lib/Target/ARM/ARMSubtarget.cpp
@@ -185,6 +185,18 @@
return false;
}
+unsigned ARMSubtarget::getMispredictionPenalty() const {
+ // If we have a reasonable estimate of the pipeline depth, then we can
+ // estimate the penalty of a misprediction based on that.
+ if (isCortexA8())
+ return 13;
+ else if (isCortexA9())
+ return 8;
+
+ // Otherwise, just return a sensible default.
+ return 10;
+}
+
bool ARMSubtarget::enablePostRAScheduler(
CodeGenOpt::Level OptLevel,
TargetSubtarget::AntiDepBreakMode& Mode,