Move bounds of far branch

tomeksowi · tomeksowi · commit 594f8349caf1 · 2025-10-13T17:02:59.000+02:00
diff --git a/src/coreclr/jit/emit.cpp b/src/coreclr/jit/emit.cpp
@@ -5049,9 +5049,11 @@ void emitter::emitJumpDistBind()
             nsd = B_DIST_SMALL_MAX_NEG;
             psd = B_DIST_SMALL_MAX_POS;
 
+            // 2 instructions: "reverse cmp-and-branch; jal offset;"
+            // Move bounds to the right by 'ssz' to account for the reversed branch instruction size.
             msz = sizeof(code_t) * 2;
-            nmd = J_DIST_SMALL_MAX_NEG;
-            pmd = J_DIST_SMALL_MAX_POS;
+            nmd = J_DIST_SMALL_MAX_NEG + ssz;
+            pmd = J_DIST_SMALL_MAX_POS + ssz;
         }
         else if (emitIsUncondJump(jmp))
         {

Original file line number	Diff line number	Diff line change
`@@ -5049,9 +5049,11 @@ void emitter::emitJumpDistBind()`
`5049`	`5049`	`nsd = B_DIST_SMALL_MAX_NEG;`
`5050`	`5050`	`psd = B_DIST_SMALL_MAX_POS;`
`5051`	`5051`
	`5052`	`+ // 2 instructions: "reverse cmp-and-branch; jal offset;"`
	`5053`	`+ // Move bounds to the right by 'ssz' to account for the reversed branch instruction size.`
`5052`	`5054`	`msz = sizeof(code_t) * 2;`
`5053`		`- nmd = J_DIST_SMALL_MAX_NEG;`
`5054`		`- pmd = J_DIST_SMALL_MAX_POS;`
	`5055`	`+ nmd = J_DIST_SMALL_MAX_NEG + ssz;`
	`5056`	`+ pmd = J_DIST_SMALL_MAX_POS + ssz;`
`5055`	`5057`	`}`
`5056`	`5058`	`else if (emitIsUncondJump(jmp))`
`5057`	`5059`	`{`