lib/CodeGen/LiveIntervalAnalysis.cpp: [PR9590] Don't use std::pow(float,float) here.

We don't expect the real "powf()" on some hosts (and powf() would be available on other hosts).
For consistency, std::pow(double,double) may be called instead.
Or, precision issue might attack us, to see unstable regalloc and stack coloring.

llvm-svn: 128629

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index d1de6a85398..68bd0a60c98 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1715,7 +1715,9 @@ LiveIntervals::getSpillWeight(bool isDef, bool isUse, unsigned loopDepth) {
   // overflow a float. This expression behaves like 10^d for small d, but is
   // more tempered for large d. At d=200 we get 6.7e33 which leaves a bit of
   // headroom before overflow.
-  float lc = std::pow(1 + (100.0f / (loopDepth+10)), (float)loopDepth);
+  // By the way, powf() might be unavailable here. For consistency,
+  // We may take pow(double,double).
+  float lc = std::pow(1 + (100.0 / (loopDepth + 10)), (double)loopDepth);
 
   return (isDef + isUse) * lc;
 }