[Openmp-commits] [openmp] Add openmp support to System z (PR #66081)

[Ilya Leoshkevich via Openmp-commits]

================
@@ -2252,6 +2252,150 @@ __kmp_invoke_microtask:
 
 #endif /* KMP_ARCH_VE */
 
+#if KMP_ARCH_S390X
+
+//------------------------------------------------------------------------
+//
+// typedef void (*microtask_t)(int *gtid, int *tid, ...);
+//
+// int __kmp_invoke_microtask(microtask_t pkfn, int gtid, int tid, int argc,
+//                            void *p_argv[]
+// #if OMPT_SUPPORT
+//                            ,
+//                            void **exit_frame_ptr
+// #endif
+//                            ) {
+// #if OMPT_SUPPORT
+//   *exit_frame_ptr = OMPT_GET_FRAME_ADDRESS(0);
+// #endif
+//
+//   (*pkfn)(&gtid, &tid, argv[0], ...);
+//
+//   return 1;
+// }
+//
+// Parameters:
+//   r2: pkfn
+//   r3: gtid
+//   r4: tid
+//   r5: argc
+//   r6: p_argv
+//   SP+160: exit_frame_ptr
+//
+// Locals:
+//   __gtid: gtid param pushed on stack so can pass &gtid to pkfn
+//   __tid: tid param pushed on stack so can pass &tid to pkfn
+//
+// Temp. registers:
+//
+//  r0: used to fetch argv slots
+//  r7: used as temporary for number of remaining pkfn parms
+//  r8: argv
+//  r9: pkfn
+//  r10: stack size
+//  r11: previous fp
+//  r12: stack parameter area
+//  r13: argv slot
+//
+// return: r2 (always 1/TRUE)
+//
+
+// -- Begin __kmp_invoke_microtask
+// mark_begin;
+	.text
+	.globl	__kmp_invoke_microtask
+	.p2align	1
+	.type	__kmp_invoke_microtask, at function
+__kmp_invoke_microtask:
+	.cfi_startproc
+
+	stmg	%r6,%r14,48(%r15)
+	lgr	%r11,%r15
+	.cfi_def_cfa	%r15, 0
+	.cfi_offset	%r15, 0
+
+	// Compute the dynamic stack size:
+	//
+	// - We need 8 bytes for storing 'gtid' and 'tid', so we can pass them by
+	//   reference
+	// - We need 8 bytes for each argument that cannot be passed to the 'pkfn'
+	//   function by register. Given that we have 5 of such registers (r[2-6])
+	//   and two + 'argc' arguments (consider &gtid and &tid), we need to
+	//   reserve max(0, argc - 3)*8 extra bytes
+	//
+	// The total number of bytes is then max(0, argc - 3)*8 + 8
+
+	lgr	%r10,%r5
+	aghi	%r10,-2
+	jnm	0f
+	lghi	%r10,0
+0:
+	sllg	%r10,%r10,3
+	lgr	%r12,%r10
+	aghi	%r10,176
+	sgr 	%r15,%r10
+	agr	%r12,%r15
+	stg	%r11,0(%r15)
+
+	lgr	%r9,%r2			// pkfn
+
+#if OMPT_SUPPORT
+	// Save frame pointer into exit_frame
+	lg	%r8,160(%r11)
+	stg	%r15,0(%r8)
+#endif
+
+	// Prepare arguments for the pkfn function (first 8 using a0-a7 registers)
----------------
iii-i wrote:

`(first 8 using a0-a7 registers)` looks like a leftover.

https://github.com/llvm/llvm-project/pull/66081