[llvm] ec8f4fd - [Support] Workaround compiler bug in MSVC

[Tom Stellard via llvm-commits]

Author: Tom Stellard
Date: 2022-07-26T12:55:10-07:00
New Revision: ec8f4fd68cd401a0ba41bb160d6acce670486fab

URL: https://github.com/llvm/llvm-project/commit/ec8f4fd68cd401a0ba41bb160d6acce670486fab
DIFF: https://github.com/llvm/llvm-project/commit/ec8f4fd68cd401a0ba41bb160d6acce670486fab.diff

LOG: [Support] Workaround compiler bug in MSVC

https://developercommunity.visualstudio.com/t/Prev-Issue---with-__assume-isnan-/1597317

This was causing unittest failures on Windows for the GitHub actions
based CI we use in the release branches.

Failed Tests (2):
  LLVM-Unit :: Support/./SupportTests.exe/FormatVariadicTest.BigTest
  LLVM-Unit :: Support/./SupportTests.exe/NativeFormatTest.BoundaryTests

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D129822

Added: 
    

Modified: 
    llvm/lib/Support/NativeFormatting.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Support/NativeFormatting.cpp b/llvm/lib/Support/NativeFormatting.cpp
index 8a69f75132555..e9854d093d4f2 100644
--- a/llvm/lib/Support/NativeFormatting.cpp
+++ b/llvm/lib/Support/NativeFormatting.cpp
@@ -262,5 +262,11 @@ size_t llvm::getDefaultPrecision(FloatStyle Style) {
   case FloatStyle::Percent:
     return 2; // Number of decimal places.
   }
+  // Workaround for MSVC bug in VS2022:
+  // https://developercommunity.visualstudio.com/t/Prev-Issue---with-__assume-isnan-/1597317
+  // llvm_unreachable expands to __assume(false) with MSVC which triggers the
+  // bug.
+#ifndef _MSC_VER
   llvm_unreachable("Unknown FloatStyle enum");
+#endif
 }