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Avoid excess precision issues that lead to generating host-compiler-specific code.

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Switch lowering probably shouldn't be using FP for this.  This resolves PR9581.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129199 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2011-04-09 06:57:13 +00:00
parent 9055ccdb6b
commit c3e4e59d10
1 changed files with 6 additions and 2 deletions
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8
lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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@ -2019,9 +2019,13 @@ bool SelectionDAGBuilder::handleBTSplitSwitchCase(CaseRec& CR,
APInt Range = ComputeRange(LEnd, RBegin);
assert((Range - 2ULL).isNonNegative() &&
"Invalid case distance");
double LDensity = (double)LSize.roundToDouble() /
// Use volatile double here to avoid excess precision issues on some hosts,
// e.g. that use 80-bit X87 registers.
volatile double LDensity =
(double)LSize.roundToDouble() /
(LEnd - First + 1ULL).roundToDouble();
double RDensity = (double)RSize.roundToDouble() /
volatile double RDensity =
(double)RSize.roundToDouble() /
(Last - RBegin + 1ULL).roundToDouble();
double Metric = Range.logBase2()*(LDensity+RDensity);
// Should always split in some non-trivial place