Change minimum gcc version for POWER10

As the MMA patches for POWER10 are backported to gcc10.2, changing
the minimum gcc version needed to build OpenBLAS for POWER10.

Makefile.system

@@ -286,6 +286,8 @@ GCCVERSIONEQ5 := $(shell expr `$(CC) -dumpversion | cut -f1 -d.` = 5)
 GCCVERSIONGT5 := $(shell expr `$(CC) -dumpversion | cut -f1 -d.` \> 5)
 GCCVERSIONGTEQ7 := $(shell expr `$(CC) -dumpversion | cut -f1 -d.` \>= 7)
 GCCVERSIONGTEQ9 := $(shell expr `$(CC) -dumpversion | cut -f1 -d.` \>= 9)
+GCCVERSIONGTEQ11 := $(shell expr `$(CC) -dumpversion | cut -f1 -d.` \>= 11)
+GCCVERSIONGTEQ10 := $(shell expr `$(CC) -dumpversion | cut -f1 -d.` \>= 10)
 # Note that the behavior of -dumpversion is compile-time-configurable for
 # gcc-7.x and newer. Use -dumpfullversion there
 ifeq ($(GCCVERSIONGTEQ7),1)
@@ -619,9 +621,12 @@ DYNAMIC_CORE += POWER9
 else
 $(info, OpenBLAS: Your gcc version is too old to build the POWER9 kernels.)
 endif
-GCCVERSIONGTEQ11 := $(shell expr `$(CC) -dumpversion | cut -f1 -d.` \>= 11)
 ifeq ($(GCCVERSIONGTEQ11), 1)
 DYNAMIC_CORE += POWER10
+else ifeq ($(GCCVERSIONEQ10), 1)
+ifeq ($(GCCMINORVERSIONGTEQ2), 1)
+DYNAMIC_CORE += POWER10
+endif
 else
 $(info, OpenBLAS: Your gcc version is too old to build the POWER10 kernels.)
 endif

driver/others/dynamic_power.c

@@ -6,7 +6,11 @@ extern gotoblas_t gotoblas_POWER8;
 #if (!defined __GNUC__) || ( __GNUC__ >= 6)
 extern gotoblas_t gotoblas_POWER9;
 #endif
-#if (!defined __GNUC__) || ( __GNUC__ >= 11)
+#if (!defined __GNUC__) || ( __GNUC__ >= 11) \
+     || (__GNUC__ == 10 && __GNUC_MINOR__ >= 2)
+#define HAVE_P10_SUPPORT 1
+#endif
+#ifdef HAVE_P10_SUPPORT
 extern gotoblas_t gotoblas_POWER10;
 #endif
 
@@ -28,7 +32,7 @@ char *gotoblas_corename(void) {
 #if (!defined __GNUC__) || ( __GNUC__ >= 6)
 	if (gotoblas == &gotoblas_POWER9)	return corename[3];
 #endif
-#if (!defined __GNUC__) || ( __GNUC__ >= 11)
+#ifdef HAVE_P10_SUPPORT
 	if (gotoblas == &gotoblas_POWER10)	return corename[4];
 #endif
 	return corename[0];
@@ -44,7 +48,7 @@ static gotoblas_t *get_coretype(void) {
 	if (__builtin_cpu_is("power9"))
 		return &gotoblas_POWER9;
 #endif
-#if (!defined __GNUC__) || ( __GNUC__ >= 11)
+#ifdef HAVE_P10_SUPPORT
 	if (__builtin_cpu_supports ("arch_3_1") && __builtin_cpu_supports ("mma"))
 		return &gotoblas_POWER10;
 #endif
@@ -73,7 +77,7 @@ static gotoblas_t *force_coretype(char * coretype) {
 #if (!defined __GNUC__) || ( __GNUC__ >= 6)
 	case  3: return (&gotoblas_POWER9);
 #endif
-#if (!defined __GNUC__) || ( __GNUC__ >= 11)
+#ifdef HAVE_P10_SUPPORT
 	case  4: return (&gotoblas_POWER10);
 #endif
 	default: return NULL;