From: NAKAMURA Takumi <geek4civic@gmail.com>
Date: Thu, 31 Mar 2011 12:11:33 +0000 (+0000)
Subject: lib/CodeGen/LiveIntervalAnalysis.cpp: [PR9590] Don't use std::pow(float,float) here.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=dc5198bac7e3f9b61617c8c46a1c28a84daa9325;hp=00e00d693c3991d85ffebf305ddbfd5dfb99ead6;p=oota-llvm.git

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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128629 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index d1de6a85398..68bd0a60c98 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/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;
 }