[PATCH] D108679: Restrict ARM IT Blocks on Windows

[Daniel Paoliello via Phabricator via llvm-commits]

dpaoliello created this revision.
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Per Microsoft's documentation (https://docs.microsoft.com/en-us/cpp/build/overview-of-arm-abi-conventions?view=msvc-160#it-instructions) ARM IT Blocks should be restricted as if targeting ARMv8, even on older versions of ARM.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D108679

Files:
  llvm/lib/Target/ARM/ARMSubtarget.cpp


Index: llvm/lib/Target/ARM/ARMSubtarget.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -235,9 +235,12 @@
   if (isTargetMachO() && isTargetIOS() && getTargetTriple().isOSVersionLT(5, 0))
     SupportsTailCall = false;
 
+  // Multi-instruction IT Blocks have been deprecated in ARMv8, additionally
+  // Windows does not permit them, even for older ARM versions.
+
   switch (IT) {
   case DefaultIT:
-    RestrictIT = hasV8Ops() && !hasMinSize();
+    RestrictIT = (hasV8Ops() && !hasMinSize()) || isTargetWindows();
     break;
   case RestrictedIT:
     RestrictIT = true;


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