JIT: enable cross-block local assertion prop (#94689)

Enable cross-block assertion prop by default.

Disable via
```
DOTNET_JitEnableCrossBlockLocalAssertionProp=0 
```
or selectively enable via
```
DOTNET_JitEnableCrossBlockLocalAssertionPropRange=<hash ranges>
```

Author: AndyAyersMS

src/coreclr/jit/fgopt.cpp

@@ -2881,6 +2881,13 @@ bool Compiler::fgOptimizeEmptyBlock(BasicBlock* block)
                 break;
             }
 
+            // Don't remove the fgEntryBB
+            //
+            if (opts.IsOSR() && (block == fgEntryBB))
+            {
+                break;
+            }
+
 #if defined(FEATURE_EH_FUNCLETS)
             /* Don't remove an empty block that is in a different EH region
              * from its successor block, if the block is the target of a

src/coreclr/jit/jitconfigvalues.h

@@ -656,7 +656,7 @@ CONFIG_INTEGER(JitEnableHeadTailMerge, W("JitEnableHeadTailMerge"), 1)
 CONFIG_INTEGER(JitEnablePhysicalPromotion, W("JitEnablePhysicalPromotion"), 1)
 
 // Enable cross-block local assertion prop
-CONFIG_INTEGER(JitEnableCrossBlockLocalAssertionProp, W("JitEnableCrossBlockLocalAssertionProp"), 0)
+CONFIG_INTEGER(JitEnableCrossBlockLocalAssertionProp, W("JitEnableCrossBlockLocalAssertionProp"), 1)
 
 #if defined(DEBUG)
 // JitFunctionFile: Name of a file that contains a list of functions. If the currently compiled function is in the

src/tests/JIT/Directed/debugging/debuginfo/tester.csproj

@@ -13,6 +13,7 @@
     <!-- These expectedly interfere with debug info -->
     <CLRTestEnvironmentVariable Include="DOTNET_JitNoForwardSub" Value="1" />
     <CLRTestEnvironmentVariable Include="DOTNET_JitEnableHeadTailMerge" Value="0" />
+    <CLRTestEnvironmentVariable Include="DOTNET_JitEnableCrossBlockLocalAssertionProp" Value="0" />
 
     <ProjectReference Include="tests_d.ilproj" Aliases="tests_d" />
     <ProjectReference Include="tests_r.ilproj" Aliases="tests_r" />