Restore updated implementation of arm32 coroutine code, but prefer ucontext.

ioquatix · ioquatix · commit acb67472c7da · 2019-06-26T22:02:28.000+12:00
diff --git a/configure.ac b/configure.ac
@@ -2272,6 +2272,9 @@ AS_CASE(["$rb_cv_fiber_coroutine"], [yes|''], [
         [x64-mingw32], [
             rb_cv_fiber_coroutine=win64
         ],
+        [armv7*-linux-*], [
+            rb_cv_fiber_coroutine=ucontext
+        ],
         [aarch64-linux], [
             rb_cv_fiber_coroutine=arm64
         ],
diff --git a/coroutine/arm32/Context.S b/coroutine/arm32/Context.S
@@ -9,6 +9,14 @@
 
 .globl coroutine_transfer
 coroutine_transfer:
-	stmia r1!, {r4-r11,sp,lr}
-	ldmia r0!, {r4-r11,sp,pc}
-	bx lr
+	# Save caller state (8 registers + return address)
+	push {r4-r11,lr}
+	
+	# Save caller stack pointer
+	str sp, [r0]
+	
+	# Restore callee stack pointer
+	ldr sp, [r1]
+	
+	# Restore callee state (8 registers program counter)
+	pop {r4-r11,pc}
diff --git a/coroutine/arm32/Context.h b/coroutine/arm32/Context.h
@@ -12,7 +12,7 @@
 
 #define COROUTINE __attribute__((noreturn)) void
 
-enum {COROUTINE_REGISTERS = 9};
+enum {COROUTINE_REGISTERS = 8};
 
 struct coroutine_context
 {

Original file line number	Diff line number	Diff line change
`@@ -12,7 +12,7 @@`
`12`	`12`
`13`	`13`	`#define COROUTINE __attribute__((noreturn)) void`
`14`	`14`
`15`		`-enum {COROUTINE_REGISTERS = 9};`
	`15`	`+enum {COROUTINE_REGISTERS = 8};`
`16`	`16`
`17`	`17`	`struct coroutine_context`
`18`	`18`	`{`