From: Dmitry Stogov <dmitry@zend.com>
Date: Thu, 7 May 2020 21:48:17 +0000 (+0300)
Subject: Avoid loop throgh side_exit from the first trace instruction.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ef45d4d69851fc59ee327e03b5ed67569297a6f7;p=php

Avoid loop throgh side_exit from the first trace instruction.
---

diff --git a/ext/opcache/jit/zend_jit_trace.c b/ext/opcache/jit/zend_jit_trace.c
index 46455f8d54..5523ecacbd 100644
--- a/ext/opcache/jit/zend_jit_trace.c
+++ b/ext/opcache/jit/zend_jit_trace.c
@@ -4895,6 +4895,7 @@ int ZEND_FASTCALL zend_jit_trace_exit(uint32_t exit_num, zend_jit_registers_buf
 {
 	uint32_t trace_num = (uint32_t)(uintptr_t)EG(reserved)[zend_func_info_rid];
 	zend_execute_data *execute_data = EG(current_execute_data);
+	const zend_op *orig_opline = EX(opline);
 	const zend_op *opline;
 	zend_jit_trace_info *t = &zend_jit_traces[trace_num];
 
@@ -4922,7 +4923,7 @@ int ZEND_FASTCALL zend_jit_trace_exit(uint32_t exit_num, zend_jit_registers_buf
 	}
 
 	if (EG(vm_interrupt)) {
-		return 0;
+		return 1;
 	/* Lock-free check if the side trace was already JIT-ed or blacklist-ed in another process */
 	} else if (t->exit_info[exit_num].flags & (ZEND_JIT_EXIT_JITED|ZEND_JIT_EXIT_BLACKLISTED)) {
 		return 0;
@@ -4949,12 +4950,14 @@ int ZEND_FASTCALL zend_jit_trace_exit(uint32_t exit_num, zend_jit_registers_buf
 				fprintf(stderr, "---- EXIT %d/%d blacklisted\n",
 					trace_num, exit_num);
 			}
+			return 0;
 		}
 	} else if (zend_jit_trace_exit_is_hot(trace_num, exit_num)) {
 		return zend_jit_trace_hot_side(execute_data, trace_num, exit_num);
 	}
 
-	return 0;
+	/* Return 1 to call original handler instead of the same JIT-ed trace */
+	return (orig_opline == t->opline && EX(opline) == orig_opline);
 }
 
 static zend_always_inline uint8_t zend_jit_trace_supported(const zend_op *opline)
diff --git a/ext/opcache/jit/zend_jit_x86.dasc b/ext/opcache/jit/zend_jit_x86.dasc
index a46d077789..e2a233f271 100644
--- a/ext/opcache/jit/zend_jit_x86.dasc
+++ b/ext/opcache/jit/zend_jit_x86.dasc
@@ -2383,28 +2383,17 @@ static int zend_jit_trace_exit_stub(dasm_State **Dst)
 	|	add r4, 8*4+8*8 /* CPU regs + SSE regs */
 	|.endif
 
-	|	// check for interrupt (try to avoid this ???)
-	|	MEM_OP2_1_ZTS cmp, byte, executor_globals, vm_interrupt, 0, r0
-	|	jne ->interrupt_handler
+	|	test eax, eax
+	|	jne >1
 
 	|	// execute_data = EG(current_execute_data)
 	|	MEM_OP2_2_ZTS mov, FP, aword, executor_globals, current_execute_data, r0
-	|	test eax, eax
-	|	jl ->trace_halt
 	|	// opline = EX(opline)
 	|	LOAD_OPLINE
 
 	if (zend_jit_vm_kind == ZEND_VM_KIND_HYBRID) {
-#if 1
-		//TODO: this doesn't work for exit from first instruction ???
 		|	add r4, HYBRID_SPAD
 		|	JMP_IP
-#else
-		|	mov r0, EX->func
-		|	mov r1, aword [r0 + offsetof(zend_op_array, reserved[zend_func_info_rid])]
-		|	mov r1, aword [r1 + offsetof(zend_jit_op_array_trace_extension, offset)]
-		|	jmp aword [IP + r1]
-#endif
 	} else if (GCC_GLOBAL_REGS) {
 		|	add r4, SPAD // stack alignment
 		|	JMP_IP
@@ -2416,6 +2405,44 @@ static int zend_jit_trace_exit_stub(dasm_State **Dst)
 		|	ret
 	}
 
+	|1:
+	|	jl ->trace_halt
+
+	|	// execute_data = EG(current_execute_data)
+	|	MEM_OP2_2_ZTS mov, FP, aword, executor_globals, current_execute_data, r0
+	|	// opline = EX(opline)
+	|	LOAD_OPLINE
+
+	|	// check for interrupt (try to avoid this ???)
+	|	MEM_OP2_1_ZTS cmp, byte, executor_globals, vm_interrupt, 0, r0
+	|	jne ->interrupt_handler
+
+	if (zend_jit_vm_kind == ZEND_VM_KIND_HYBRID) {
+		|	add r4, HYBRID_SPAD
+		|	mov r0, EX->func
+		|	mov r0, aword [r0 + offsetof(zend_op_array, reserved[zend_func_info_rid])]
+		|	mov r0, aword [r0 + offsetof(zend_jit_op_array_trace_extension, offset)]
+		|	jmp aword [IP + r0]
+	} else if (GCC_GLOBAL_REGS) {
+		|	add r4, SPAD // stack alignment
+		|	mov r0, EX->func
+		|	mov r0, aword [r0 + offsetof(zend_op_array, reserved[zend_func_info_rid])]
+		|	mov r0, aword [r0 + offsetof(zend_jit_op_array_trace_extension, offset)]
+		|	jmp aword [IP + r0]
+	} else {
+		|	mov IP, aword EX->opline
+		|	mov FCARG1a, FP
+		|	mov r0, EX->func
+		|	mov r0, aword [r0 + offsetof(zend_op_array, reserved[zend_func_info_rid])]
+		|	mov r0, aword [r0 + offsetof(zend_jit_op_array_trace_extension, offset)]
+		|	call aword [IP + r0]
+		|	mov FP, aword T2 // restore FP
+		|	mov RX, aword T3 // restore IP
+		|	add r4, NR_SPAD // stack alignment
+		|	mov r0, 1 // ZEND_VM_ENTER
+		|	ret
+	}
+
 	return 1;
 }