[clang] [llvm] Fix Windows EH IP2State tables (remove +1 bias) (PR #144745)

[via llvm-commits]

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@@ -37,9 +37,11 @@ cond.end:                                         ; preds = %entry, %cond.true
 ; CHECK: testq
 ; CHECK: je
 ; CHECK: callq alloc
+; CHECK-NEXT: nop
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sivadeilra wrote:

I believe it is necessary because it is immediately before `.seh_startepilogue`.  If `alloc` unwinds, then IP2State will point into the epilogue, and the unwinder won't run the handler for that region.  MSVC should also insert a NOP in this situation.

https://github.com/llvm/llvm-project/pull/144745