From f1c9552907c8d47c2116840a5ffc5c17039f307f Mon Sep 17 00:00:00 2001
From: Jan Vorlicek <jan.vorlicek@volny.cz>
Date: Tue, 4 Jan 2022 23:51:52 +0100
Subject: [PATCH] Fix build with Clang 13 (#63314)

* Fix clang 13 induced runtime issues (#62170)

The clang 13 optimizer started to assume that "this" pointer is always
properly aligned. That lead to elimination of some code that was actually
needed.
It also takes pointer aliasing rules more strictly in one place in jit.
That caused the optimizer to falsely assume that a callee with an argument
passed by reference is not modifying that argument and used a stale
copy of the original value at the caller site.

This change fixes both of the issues. With this fix, runtime compiled
using clang 13 seems to be fully functional.
---
 src/inc/corhlpr.h           | 8 ++++----
 src/jit/bitsetasshortlong.h | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/inc/corhlpr.h b/src/inc/corhlpr.h
index 5b263a538230..c512069fca4a 100644
--- a/src/inc/corhlpr.h
+++ b/src/inc/corhlpr.h
@@ -335,7 +335,7 @@ struct COR_ILMETHOD_SECT
     const COR_ILMETHOD_SECT* Next() const   
     {
         if (!More()) return(0);
-        return ((COR_ILMETHOD_SECT*)(((BYTE *)this) + DataSize()))->Align();
+        return ((COR_ILMETHOD_SECT*)Align(((BYTE *)this) + DataSize()));
     }
 
     const BYTE* Data() const 
@@ -373,9 +373,9 @@ struct COR_ILMETHOD_SECT
         return((AsSmall()->Kind & CorILMethod_Sect_FatFormat) != 0); 
     }
 
-    const COR_ILMETHOD_SECT* Align() const        
+    static const void* Align(const void* p)
     { 
-        return((COR_ILMETHOD_SECT*) ((((UINT_PTR) this) + 3) & ~3));  
+        return((void*) ((((UINT_PTR) p) + 3) & ~3));
     }
 
 protected:
@@ -578,7 +578,7 @@ typedef struct tagCOR_ILMETHOD_FAT : IMAGE_COR_ILMETHOD_FAT
 
     const COR_ILMETHOD_SECT* GetSect() const {
         if (!More()) return (0);
-        return(((COR_ILMETHOD_SECT*) (GetCode() + GetCodeSize()))->Align());
+        return(((COR_ILMETHOD_SECT*) COR_ILMETHOD_SECT::Align(GetCode() + GetCodeSize())));
     }
 } COR_ILMETHOD_FAT;
 
diff --git a/src/jit/bitsetasshortlong.h b/src/jit/bitsetasshortlong.h
index 17e0e3a69cba..0c40283ce51a 100644
--- a/src/jit/bitsetasshortlong.h
+++ b/src/jit/bitsetasshortlong.h
@@ -346,7 +346,7 @@ class BitSetOps</*BitSetType*/ BitSetShortLongRep,
     {
         if (IsShort(env))
         {
-            (size_t&)out = (size_t)out & ((size_t)gen | (size_t)in);
+            out = (BitSetShortLongRep)((size_t)out & ((size_t)gen | (size_t)in));
         }
         else
         {
@@ -362,7 +362,7 @@ class BitSetOps</*BitSetType*/ BitSetShortLongRep,
     {
         if (IsShort(env))
         {
-            (size_t&)in = (size_t)use | ((size_t)out & ~(size_t)def);
+            in = (BitSetShortLongRep)((size_t)use | ((size_t)out & ~(size_t)def));
         }
         else
         {