When patching JITed code after become of a class, the class index can look like a negative number

smalltalksrc/VMMaker/CogAbstractInstruction.class.st

@@ -1057,7 +1057,7 @@ CogAbstractInstruction >> getOperandsWithFormat: format [
 						ifTrue: [ (operand > 16 and: [ opcode ~= Label ]) 
 							ifTrue: [ 
 								(operand allMask: 16r80000000) 
-									ifTrue: [ strOperands add: operand, '/', operand signedIntFromLong ].
+									ifTrue: [ strOperands add: operand printString, '/', operand signedIntFromLong printString ].
 									strOperands add: operand asString, '/', (operand hex)]
 							ifFalse: [ 
 								strOperands add: operand.

smalltalksrc/VMMaker/CogIA32Compiler.class.st

@@ -3646,7 +3646,11 @@ CogIA32Compiler >> hasThreeAddressArithmetic [
 { #category : 'inline cacheing' }
 CogIA32Compiler >> inlineCacheTagAt: callSiteReturnAddress [
 	"Answer the inline cache tag for the return address of a send."
-	^self literalBeforeFollowingAddress: callSiteReturnAddress - 5
+
+	<returnTypeC: #usqInt>
+
+	^ (self literalBeforeFollowingAddress: callSiteReturnAddress - 5)
+		  bitAnd: 1 << objectMemory classIndexFieldWidth - 1
 ]
 
 { #category : 'disassembly' }

smalltalksrc/VMMaker/CogInLineLiteralsARMCompiler.class.st

@@ -50,8 +50,15 @@ CogInLineLiteralsARMCompiler >> getDefaultCogCodeSize [
 { #category : 'inline cacheing' }
 CogInLineLiteralsARMCompiler >> inlineCacheTagAt: callSiteReturnAddress [
 	"Answer the inline cache tag for the return address of a send."
-	self assert: (self instructionIsBL: (self instructionBeforeAddress: callSiteReturnAddress)).
-	^self extract32BitOperandFrom4InstructionsPreceding: callSiteReturnAddress - 4
+
+	<returnTypeC: #usqInt>
+
+	self assert: (self instructionIsBL:
+			 (self instructionBeforeAddress: callSiteReturnAddress)).
+
+	^ (self extract32BitOperandFrom4InstructionsPreceding:
+		   callSiteReturnAddress - 4) bitAnd:
+		  1 << objectMemory classIndexFieldWidth - 1
 ]
 
 { #category : 'testing' }

smalltalksrc/VMMaker/CogInLineLiteralsX64Compiler.class.st

@@ -164,7 +164,11 @@ CogInLineLiteralsX64Compiler >> getDefaultCogCodeSize [
 { #category : 'inline cacheing' }
 CogInLineLiteralsX64Compiler >> inlineCacheTagAt: callSiteReturnAddress [
 	"Answer the inline cache tag for the return address of a send."
-	^self literal32BeforeFollowingAddress: callSiteReturnAddress - 5
+
+	<returnTypeC: #usqInt>
+
+	^ (self literal32BeforeFollowingAddress: callSiteReturnAddress - 5)
+		  bitAnd: 1 << objectMemory classIndexFieldWidth - 1
 ]
 
 { #category : 'testing' }

smalltalksrc/VMMaker/CogMIPSELCompiler.class.st

@@ -1908,6 +1908,8 @@ CogMIPSELCompiler >> inlineCacheTagAt: callSiteReturnAddress [
 	 ...  <-- callSiteReturnAddress"
 
 	<var: #callSiteReturnAddress type: #usqInt>
+	<returnTypeC: #usqInt>
+
 	self assert: (self opcodeAtAddress: callSiteReturnAddress - 24) = LUI.
 	self assert: (self opcodeAtAddress: callSiteReturnAddress - 20) = ORI.
 	self assert: (self opcodeAtAddress: callSiteReturnAddress - 16) = LUI.
@@ -1916,7 +1918,8 @@ CogMIPSELCompiler >> inlineCacheTagAt: callSiteReturnAddress [
 	self assert: (self functionAtAddress: callSiteReturnAddress - 8) = JALR.
 	self assert: (objectMemory longAt: callSiteReturnAddress - 4) = self nop.
 
-	^self literalAtAddress: callSiteReturnAddress - 20
+	^(self literalAtAddress: callSiteReturnAddress - 20) bitAnd:
+		  1 << objectMemory classIndexFieldWidth - 1
 ]
 
 { #category : 'disassembly' }

smalltalksrc/VMMaker/CogOutOfLineLiteralsARMCompiler.class.st

@@ -51,8 +51,11 @@ CogOutOfLineLiteralsARMCompiler >> getDefaultCogCodeSize [
 
 { #category : 'inline cacheing' }
 CogOutOfLineLiteralsARMCompiler >> inlineCacheTagAt: callSiteReturnAddress [
-	<inline: true>
-	^objectMemory uint32AtPointer: (self pcRelativeAddressAt: (callSiteReturnAddress - 8) asUnsignedInteger)
+
+	<returnTypeC: #usqInt>
+
+	^(objectMemory uint32AtPointer: (self pcRelativeAddressAt: (callSiteReturnAddress - 8) asUnsignedInteger)) bitAnd:
+		  1 << objectMemory classIndexFieldWidth - 1
 ]
 
 { #category : 'testing' }

smalltalksrc/VMMaker/CogOutOfLineLiteralsARMv8Compiler.class.st

@@ -207,8 +207,12 @@ CogOutOfLineLiteralsARMv8Compiler >> getDefaultCogCodeSize [
 
 { #category : 'inline cacheing' }
 CogOutOfLineLiteralsARMv8Compiler >> inlineCacheTagAt: callSiteReturnAddress [
-	<inline: true>
-	^objectMemory unsignedLongAt: (self pcRelativeAddressAt: (callSiteReturnAddress - 8) asUnsignedInteger)
+
+	<returnTypeC: #usqInt>
+
+	^ (objectMemory unsignedLongAt: (self pcRelativeAddressAt:
+			    (callSiteReturnAddress - 8) asUnsignedInteger)) bitAnd:
+		  1 << objectMemory classIndexFieldWidth - 1
 ]
 
 { #category : 'testing' }

smalltalksrc/VMMaker/SpurMemoryManager.class.st

@@ -3697,6 +3697,7 @@ SpurMemoryManager >> classFormatFromInstFormat: instFormat [
 
 { #category : 'header format' }
 SpurMemoryManager >> classIndexFieldWidth [
+	<api>
 	"22-bit class mask => ~ 4M classes"
 	^22
 ]
@@ -8166,6 +8167,7 @@ SpurMemoryManager >> isValidClassIndex: classIndex [
 SpurMemoryManager >> isValidClassTag: classIndex [
 	<api>
 	| classOrNil |
+
 	self assert: (classIndex between: 0 and: 1 << self classIndexFieldWidth - 1).
 	classOrNil := self classOrNilAtIndex: classIndex.
 	^classOrNil ~= nilObj

smalltalksrc/VMMakerTests/VMClassTagInlineReadTest.class.st

@@ -0,0 +1,62 @@
+Class {
+	#name : 'VMClassTagInlineReadTest',
+	#superclass : 'VMPrimitiveCallAbstractTest',
+	#pools : [
+		'CogRTLOpcodes'
+	],
+	#category : 'VMMakerTests-JitTests',
+	#package : 'VMMakerTests',
+	#tag : 'JitTests'
+}
+
+{ #category : 'tests' }
+VMClassTagInlineReadTest >> testLinkingWithEntryOffset [
+
+	| sendingMethod targetMethod callSiteReturn |
+	sendingMethod := self
+		                 jitMethod: (self findMethod: #methodWithSend)
+		                 selector: memory nilObject.
+
+	targetMethod := self
+		                jitMethod: (self findMethod: #yourself)
+		                selector: memory trueObject.
+
+	callSiteReturn := sendingMethod address + 16r98.
+
+	cogit
+		linkSendAt: callSiteReturn
+		in: sendingMethod
+		to: targetMethod
+		offset: cogit entryOffset
+		receiver: memory falseObject.
+
+	self assert: (cogit backend inlineCacheTagAt: callSiteReturn) equals:(memory classIndexOf: memory falseObject)
+]
+
+{ #category : 'tests' }
+VMClassTagInlineReadTest >> testLinkingWithEntryOffsetLargeClassIndex [
+
+	| sendingMethod targetMethod callSiteReturn |
+	sendingMethod := self
+		                 jitMethod: (self findMethod: #methodWithSend)
+		                 selector: memory nilObject.
+
+	targetMethod := self
+		                jitMethod: (self findMethod: #yourself)
+		                selector: memory trueObject.
+
+	callSiteReturn := sendingMethod address + 16r98.
+
+	obj := self newZeroSizedObject.
+	memory setClassIndexOf: obj to: (1 << memory classIndexFieldWidth - 5).
+
+	cogit
+		linkSendAt: callSiteReturn
+		in: sendingMethod
+		to: targetMethod
+		offset: cogit entryOffset
+		receiver: obj.
+
+
+	self assert: (cogit backend inlineCacheTagAt: callSiteReturn) equals: (1 << memory classIndexFieldWidth - 5)
+]