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V11 patch #6 of 15, Make -mpcrel the default for -mcpu=future on Linux 64-bit

Message ID 20191221000117.GF28993@ibm-toto.the-meissners.org
State New
Headers show
Series V11 patch #6 of 15, Make -mpcrel the default for -mcpu=future on Linux 64-bit | expand

Commit Message

Michael Meissner Dec. 21, 2019, 12:01 a.m. UTC
This is the same as V10 patch #8.  Once the vector extract patches are
committed, this patch flips the default to use PC-relative addressing on 64-bit
Linux systems when the uses -mcpu=future.
https://gcc.gnu.org/ml/gcc-patches/2019-12/msg00841.html

I have bootstrapped the compiler on a little endian power8 system and ran the
testsuite with no regressions.  Once the preceeding V11 patches have been
checked in, can I check these patches into the trunk?

2019-12-20  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/linux64.h (PREFIXED_ADDR_SUPPORTED_BY_OS): Set to
	1 to enable prefixed addressing if -mcpu=future.
	(PCREL_SUPPORTED_BY_OS): Set to 1 to enable PC-relative addressing
	if -mcpu=future.
	* config/rs6000/rs6000-cpus.h (ISA_FUTURE_MASKS_SERVER): Do not
	enable -mprefixed-addr or -mpcrel by default.
	(ADDRESSING_FUTURE_MASKS): New macro.
	(OTHER_FUTURE_MASKS): Use ADDRESSING_FUTURE_MASKS.
	* config/rs6000/rs6000.c (PREFIXED_ADDR_SUPPORTED_BY_OS): Disable
	prefixed addressing unless the target OS tm.h says we should
	enable it.
	(PCREL_SUPPORTED_BY_OS): Disable PC-relative addressing unless the
	target OS tm.h says we should enable it.
	(rs6000_debug_reg_global): Print whether prefixed addressing and
	PC-relative addressing is enabled by default if -mcpu=future.
	(rs6000_option_override_internal): Move setting prefixed
	addressing and PC-relative addressing after the sub-target option
	handling is done.  Only enable prefixed addressing or PC-relative
	address on -mcpu=future system if the target OS says to enable
	it.  Disallow prefixed addressing on 32-bit systems or if the
	target object file is not ELF v2.
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Patch

Index: gcc/config/rs6000/linux64.h
===================================================================
--- gcc/config/rs6000/linux64.h	(revision 279141)
+++ gcc/config/rs6000/linux64.h	(working copy)
@@ -640,3 +640,11 @@  extern int dot_symbols;
    enabling the __float128 keyword.  */
 #undef	TARGET_FLOAT128_ENABLE_TYPE
 #define TARGET_FLOAT128_ENABLE_TYPE 1
+
+/* Enable support for pc-relative and numeric prefixed addressing on the
+   'future' system.  */
+#undef  PREFIXED_ADDR_SUPPORTED_BY_OS
+#define PREFIXED_ADDR_SUPPORTED_BY_OS	1
+
+#undef  PCREL_SUPPORTED_BY_OS
+#define PCREL_SUPPORTED_BY_OS		1
Index: gcc/config/rs6000/rs6000-cpus.def
===================================================================
--- gcc/config/rs6000/rs6000-cpus.def	(revision 279141)
+++ gcc/config/rs6000/rs6000-cpus.def	(working copy)
@@ -75,15 +75,22 @@ 
 				 | OPTION_MASK_P8_VECTOR		\
 				 | OPTION_MASK_P9_VECTOR)
 
-/* Support for a future processor's features.  Do not enable -mpcrel until it
-   is fully functional.  */
+/* Support for a future processor's features.  The prefixed and pc-relative
+   addressing bits are not added here.  Instead, they are added if the target
+   OS tm.h says that it supports the addressing modes by default when
+   -mcpu=future is used.  */
 #define ISA_FUTURE_MASKS_SERVER	(ISA_3_0_MASKS_SERVER			\
-				 | OPTION_MASK_FUTURE			\
+				 | OPTION_MASK_FUTURE)
+
+/* Addressing related flags on a future processor.  These are options that need
+   to be cleared if the target OS is not capable of supporting prefixed
+   addressing at all (such as 32-bit mode or if the object file format is not
+   ELF v2).  */
+#define ADDRESSING_FUTURE_MASKS	(OPTION_MASK_PCREL			\
 				 | OPTION_MASK_PREFIXED_ADDR)
 
 /* Flags that need to be turned off if -mno-future.  */
-#define OTHER_FUTURE_MASKS	(OPTION_MASK_PCREL			\
-				 | OPTION_MASK_PREFIXED_ADDR)
+#define OTHER_FUTURE_MASKS	ADDRESSING_FUTURE_MASKS
 
 /* Flags that need to be turned off if -mno-power9-vector.  */
 #define OTHER_P9_VECTOR_MASKS	(OPTION_MASK_FLOAT128_HW		\
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c	(revision 279202)
+++ gcc/config/rs6000/rs6000.c	(working copy)
@@ -98,6 +98,16 @@ 
 #endif
 #endif
 
+/* Set up the defaults for whether prefixed addressing is used, and if it is
+   used, whether we want to turn on pc-relative support by default.  */
+#ifndef PREFIXED_ADDR_SUPPORTED_BY_OS
+#define PREFIXED_ADDR_SUPPORTED_BY_OS	0
+#endif
+
+#ifndef PCREL_SUPPORTED_BY_OS
+#define PCREL_SUPPORTED_BY_OS		0
+#endif
+
 /* Support targetm.vectorize.builtin_mask_for_load.  */
 GTY(()) tree altivec_builtin_mask_for_load;
 
@@ -2535,6 +2545,14 @@  rs6000_debug_reg_global (void)
   if (TARGET_DIRECT_MOVE_128)
     fprintf (stderr, DEBUG_FMT_D, "VSX easy 64-bit mfvsrld element",
 	     (int)VECTOR_ELEMENT_MFVSRLD_64BIT);
+
+  if (TARGET_FUTURE)
+    {
+      fprintf (stderr, DEBUG_FMT_D, "PREFIXED_ADDR_SUPPORTED_BY_OS",
+	       PREFIXED_ADDR_SUPPORTED_BY_OS);
+      fprintf (stderr, DEBUG_FMT_D, "PCREL_SUPPORTED_BY_OS",
+	       PCREL_SUPPORTED_BY_OS);
+    }
 }
 
 
@@ -4015,26 +4033,6 @@  rs6000_option_override_internal (bool gl
       rs6000_isa_flags &= ~OPTION_MASK_FLOAT128_HW;
     }
 
-  /* -mprefixed-addr (and hence -mpcrel) requires -mcpu=future.  */
-  if (TARGET_PREFIXED_ADDR && !TARGET_FUTURE)
-    {
-      if ((rs6000_isa_flags_explicit & OPTION_MASK_PCREL) != 0)
-	error ("%qs requires %qs", "-mpcrel", "-mcpu=future");
-      else if ((rs6000_isa_flags_explicit & OPTION_MASK_PREFIXED_ADDR) != 0)
-	error ("%qs requires %qs", "-mprefixed-addr", "-mcpu=future");
-
-      rs6000_isa_flags &= ~(OPTION_MASK_PCREL | OPTION_MASK_PREFIXED_ADDR);
-    }
-
-  /* -mpcrel requires prefixed load/store addressing.  */
-  if (TARGET_PCREL && !TARGET_PREFIXED_ADDR)
-    {
-      if ((rs6000_isa_flags_explicit & OPTION_MASK_PCREL) != 0)
-	error ("%qs requires %qs", "-mpcrel", "-mprefixed-addr");
-
-      rs6000_isa_flags &= ~OPTION_MASK_PCREL;
-    }
-
   /* Print the options after updating the defaults.  */
   if (TARGET_DEBUG_REG || TARGET_DEBUG_TARGET)
     rs6000_print_isa_options (stderr, 0, "after defaults", rs6000_isa_flags);
@@ -4166,12 +4164,91 @@  rs6000_option_override_internal (bool gl
   SUB3TARGET_OVERRIDE_OPTIONS;
 #endif
 
-  /* -mpcrel requires -mcmodel=medium, but we can't check TARGET_CMODEL until
-      after the subtarget override options are done.  */
-  if (TARGET_PCREL && TARGET_CMODEL != CMODEL_MEDIUM)
+  /* Enable prefixed addressing and PC-relative addressing if the target OS
+     tm.h file says that it is supported and the user did not explicitly use
+     -mprefixed-addr or -mpcrel.  At the present time, only 64-bit Linux
+     enables this.
+
+     PC-relative support also requires the medium code model.
+
+     We can't check for ELFv2 or -mcmodel=medium until after the subtarget
+     macros are run.
+
+     If prefixed addressing is disabled by default, and the user does -mpcrel,
+     don't force them to also specify -mprefixed-addr.  */
+  if (TARGET_FUTURE)
+    {
+      bool explicit_prefixed = ((rs6000_isa_flags_explicit
+				 & OPTION_MASK_PREFIXED_ADDR) != 0);
+      bool explicit_pcrel = ((rs6000_isa_flags_explicit
+			      & OPTION_MASK_PCREL) != 0);
+
+      /* Prefixed addressing requires 64-bit registers.  */
+      if (!TARGET_POWERPC64)
+	{
+	  if (TARGET_PCREL && explicit_pcrel)
+	    error ("%qs requires %qs", "-mpcrel", "-m64");
+
+	  else if (TARGET_PREFIXED_ADDR && explicit_prefixed)
+	    error ("%qs requires %qs", "-mprefixed-addr", "-m64");
+
+	  rs6000_isa_flags &= ~ADDRESSING_FUTURE_MASKS;
+	}
+
+      /* Only ELFv2 currently supports prefixed/pcrel addressing.  */
+      else if (rs6000_current_abi != ABI_ELFv2)
+	{
+	  if (TARGET_PCREL && explicit_pcrel)
+	    error ("%qs requires %qs", "-mpcrel", "-mabi=elfv2");
+
+	  else if (TARGET_PREFIXED_ADDR && explicit_prefixed)
+	    error ("%qs requires %qs", "-mprefixed-addr", "-mabi=elfv2");
+
+	  rs6000_isa_flags &= ~ADDRESSING_FUTURE_MASKS;
+	}
+
+      /* Enable defaults if desired.  */
+      else
+	{
+	  if (!explicit_prefixed
+	      && (PREFIXED_ADDR_SUPPORTED_BY_OS
+		  || TARGET_PCREL
+		  || PCREL_SUPPORTED_BY_OS))
+	    rs6000_isa_flags |= OPTION_MASK_PREFIXED_ADDR;
+
+	  if (!explicit_pcrel && PCREL_SUPPORTED_BY_OS
+	      && TARGET_PREFIXED_ADDR
+	      && TARGET_CMODEL == CMODEL_MEDIUM)
+	    rs6000_isa_flags |= OPTION_MASK_PCREL;
+	}
+
+      /* PC-relative requires the medium code model.  */
+      if (TARGET_PCREL && TARGET_CMODEL != CMODEL_MEDIUM)
+	{
+	  if ((rs6000_isa_flags_explicit & OPTION_MASK_PCREL) != 0)
+	    error ("%qs requires %qs", "-mpcrel", "-mcmodel=medium");
+
+	  rs6000_isa_flags &= ~OPTION_MASK_PCREL;
+	}
+
+    }
+
+  /* -mprefixed-addr (and hence -mpcrel) requires -mcpu=future.  */
+  if (TARGET_PREFIXED_ADDR && !TARGET_FUTURE)
     {
       if ((rs6000_isa_flags_explicit & OPTION_MASK_PCREL) != 0)
-	error ("%qs requires %qs", "-mpcrel", "-mcmodel=medium");
+	error ("%qs requires %qs", "-mpcrel", "-mcpu=future");
+      else if ((rs6000_isa_flags_explicit & OPTION_MASK_PREFIXED_ADDR) != 0)
+	error ("%qs requires %qs", "-mprefixed-addr", "-mcpu=future");
+
+      rs6000_isa_flags &= ~(OPTION_MASK_PCREL | OPTION_MASK_PREFIXED_ADDR);
+    }
+
+  /* -mpcrel requires prefixed load/store addressing.  */
+  if (TARGET_PCREL && !TARGET_PREFIXED_ADDR)
+    {
+      if ((rs6000_isa_flags_explicit & OPTION_MASK_PCREL) != 0)
+	error ("%qs requires %qs", "-mpcrel", "-mprefixed-addr");
 
       rs6000_isa_flags &= ~OPTION_MASK_PCREL;
     }