arm.c (TARGET_MAX_ANCHOR_OFFSET): New.

2008-08-28  Paul Brook  <paul@codesourcery.com>
	Mark Shinwell  <shinwell@codesourcery.com>
	Richard Earnshaw  <richard.earnshaw@arm.com>

	gcc/
	* config/arm/arm.c (TARGET_MAX_ANCHOR_OFFSET): New.
	(TARGET_MIN_ANCHOR_OFFSET): New.
	(arm_override_options): Set correct anchor ranges for Thumb-1
	and Thumb-2 if required.
	(legitimize_pic_address): Handle case involving a TLS symbol
	reference with an addend.
	(arm_optimization_options): Enable section anchors at -O1 and
	above.
	* config/arm/arm.h (OPTIMIZATION_OPTIONS): New.
	* config/arm/arm-protos.h (arm_optimization_options): New.


Co-Authored-By: Mark Shinwell <shinwell@codesourcery.com>
Co-Authored-By: Richard Earnshaw <rearnsha@arm.com>

From-SVN: r139725

3 files changed, 54 insertions, 0 deletions

diff --git a/gcc/config/arm/arm-protos.h b/gcc/config/arm/arm-protos.h
index bdf9a04..d0e408c 100644
--- a/gcc/config/arm/arm-protos.h
+++ b/gcc/config/arm/arm-protos.h
@@ -24,6 +24,7 @@
 #define GCC_ARM_PROTOS_H
 
 extern void arm_override_options (void);
+extern void arm_optimization_options (int, int);
 extern int use_return_insn (int, rtx);
 extern int arm_regno_class (int);
 extern void arm_load_pic_register (unsigned long);
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 61b1969..888a242 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -367,6 +367,15 @@ static bool arm_allocate_stack_slots_for_args (void);
 #undef TARGET_CANNOT_FORCE_CONST_MEM
 #define TARGET_CANNOT_FORCE_CONST_MEM arm_cannot_force_const_mem
 
+#undef TARGET_MAX_ANCHOR_OFFSET
+#define TARGET_MAX_ANCHOR_OFFSET 4095
+
+/* The minimum is set such that the total size of the block
+   for a particular anchor is -4088 + 1 + 4095 bytes, which is
+   divisible by eight, ensuring natural spacing of anchors.  */
+#undef TARGET_MIN_ANCHOR_OFFSET
+#define TARGET_MIN_ANCHOR_OFFSET -4088
+
 #undef TARGET_SCHED_ISSUE_RATE
 #define TARGET_SCHED_ISSUE_RATE arm_issue_rate
 
@@ -1267,6 +1276,27 @@ arm_override_options (void)
   arm_arch_iwmmxt = (insn_flags & FL_IWMMXT) != 0;
   arm_arch_hwdiv = (insn_flags & FL_DIV) != 0;
 
+  /* If we are not using the default (ARM mode) section anchor offset
+     ranges, then set the correct ranges now.  */
+  if (TARGET_THUMB1)
+    {
+      /* Thumb-1 LDR instructions cannot have negative offsets.
+         Permissible positive offset ranges are 5-bit (for byte loads),
+         6-bit (for halfword loads), or 7-bit (for word loads).
+         Empirical results suggest a 7-bit anchor range gives the best
+         overall code size.  */
+      targetm.min_anchor_offset = 0;
+      targetm.max_anchor_offset = 127;
+    }
+  else if (TARGET_THUMB2)
+    {
+      /* The minimum is set such that the total size of the block
+         for a particular anchor is 248 + 1 + 4095 bytes, which is
+         divisible by eight, ensuring natural spacing of anchors.  */
+      targetm.min_anchor_offset = -248;
+      targetm.max_anchor_offset = 4095;
+    }
+
   /* V5 code we generate is completely interworking capable, so we turn off
      TARGET_INTERWORK here to avoid many tests later on.  */
 
@@ -3493,10 +3523,22 @@ legitimize_pic_address (rtx orig, enum machine_mode mode, rtx reg)
 	  && XEXP (XEXP (orig, 0), 0) == cfun->machine->pic_reg)
 	return orig;
 
+      /* Handle the case where we have: const (UNSPEC_TLS).  */
       if (GET_CODE (XEXP (orig, 0)) == UNSPEC
 	  && XINT (XEXP (orig, 0), 1) == UNSPEC_TLS)
 	return orig;
 
+      /* Handle the case where we have:
+         const (plus (UNSPEC_TLS) (ADDEND)).  The ADDEND must be a
+         CONST_INT.  */
+      if (GET_CODE (XEXP (orig, 0)) == PLUS
+          && GET_CODE (XEXP (XEXP (orig, 0), 0)) == UNSPEC
+          && XINT (XEXP (XEXP (orig, 0), 0), 1) == UNSPEC_TLS)
+        {
+	  gcc_assert (GET_CODE (XEXP (XEXP (orig, 0), 1)) == CONST_INT);
+	  return orig;
+	}
+
       if (reg == 0)
 	{
 	  gcc_assert (can_create_pseudo_p ());
@@ -19066,4 +19108,12 @@ arm_order_regs_for_local_alloc (void)
             sizeof (thumb_core_reg_alloc_order));
 }
 
+/* Set default optimization options.  */
+void
+arm_optimization_options (int level, int size ATTRIBUTE_UNUSED)
+{
+  /* Enable section anchors by default at -O1 or higher.  */
+  flag_section_anchors = (level > 0 ? 1 : 0);
+}
+
 #include "gt-arm.h"
diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
index fd5067a..2f236e0 100644
--- a/gcc/config/arm/arm.h
+++ b/gcc/config/arm/arm.h
@@ -427,6 +427,9 @@ extern int arm_arch_hwdiv;
 
 #define OVERRIDE_OPTIONS  arm_override_options ()
 
+#define OPTIMIZATION_OPTIONS(LEVEL,SIZE)		\
+	arm_optimization_options ((LEVEL), (SIZE))
+
 /* Nonzero if PIC code requires explicit qualifiers to generate
    PLT and GOT relocs rather than the assembler doing so implicitly.
    Subtargets can override these if required.  */