Revert "Fix llvm register allocator for native/cross build differences"

In preparation for applying the fix that landed upstream, this reverts
commit 397c2693fa66508cb5e6b173650a1f3bc6c4dd4f:

  Fix llvm register allocator for native/cross build differences

  Work around an issue in LLVM's register allocator, which can cause
  slightly different i386 object files, when produced by a native or cross
  build of clang.

  This adds another volatile qualifier to a float variable declaration in
  the weightCalcHelper() function, which otherwise produces slightly
  different float results on amd64 and i386 hosts. In turn, this can lead
  to different (but equivalent) register choices, and thus non-identical
  assembly code.

  See https://github.com/llvm/llvm-project/issues/99396 for more details.

  Note this is a temporary fix, meant to merge in time for 13.4. As soon
  as upstream has a permanent solution we will import that.

PR:		276961
Reported by:	cperciva
MFC after:	3 days

(cherry picked from commit 52552d7572a6d3d7d3ce0d6862de9a9d203c5d01)

1 files changed, 1 insertions, 6 deletions

diff --git a/contrib/llvm-project/llvm/lib/CodeGen/CalcSpillWeights.cpp b/contrib/llvm-project/llvm/lib/CodeGen/CalcSpillWeights.cpp
index afde8d001f88..f3cb7fa5af61 100644
--- a/contrib/llvm-project/llvm/lib/CodeGen/CalcSpillWeights.cpp
+++ b/contrib/llvm-project/llvm/lib/CodeGen/CalcSpillWeights.cpp
@@ -256,12 +256,7 @@ float VirtRegAuxInfo::weightCalcHelper(LiveInterval &LI, SlotIndex *Start,
       return -1.0f;
     }
 
-    // FreeBSD customization: similar to the HWeight declaration below, add a
-    // volatile qualifier to avoid slightly different weight results on amd64
-    // and i386 hosts, and possibly choosing different registers in the register
-    // allocator. See <https://github.com/llvm/llvm-project/issues/99396> for
-    // more details.
-    volatile float Weight = 1.0f;
+    float Weight = 1.0f;
     if (IsSpillable) {
       // Get loop info for mi.
       if (MI->getParent() != MBB) {