Commit 2b2cfe2e authored by Bill Wendling's avatar Bill Wendling
Browse files

Merging r143006: 

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r143006 | stoklund | 2011-10-25 18:47:48 -0700 (Tue, 25 Oct 2011) | 8 lines

Don't use floating point to do an integer's job.

This code makes different decisions when compiled into x87 instructions
because of different rounding behavior.  That caused phase 2/3
miscompares on 32-bit Linux when the phase 1 compiler was built with gcc
(using x87), and the phase 2 compiler was built with clang (using SSE).

This fixes PR11200.
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llvm-svn: 143013
parent bb15689d

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

+7 −4
Original line number Diff line number Diff line
@@ -2034,14 +2034,17 @@ bool SelectionDAGBuilder::handleJTSwitchCase(CaseRec &CR, 
    return false;



  APInt Range = ComputeRange(First, Last);

  double Density = TSize.roundToDouble() / Range.roundToDouble();

  if (Density < 0.4)

  // The density is TSize / Range. Require at least 40%.

  // It should not be possible for IntTSize to saturate for sane code, but make

  // sure we handle Range saturation correctly.

  uint64_t IntRange = Range.getLimitedValue(UINT64_MAX/10);

  uint64_t IntTSize = TSize.getLimitedValue(UINT64_MAX/10);

  if (IntTSize * 10 < IntRange * 4)

    return false;



  DEBUG(dbgs() << "Lowering jump table\n"

               << "First entry: " << First << ". Last entry: " << Last << '\n'

               << "Range: " << Range

               << ". Size: " << TSize << ". Density: " << Density << "\n\n");

               << "Range: " << Range << ". Size: " << TSize << ".\n\n");



  // Get the MachineFunction which holds the current MBB.  This is used when

  // inserting any additional MBBs necessary to represent the switch.