[gcc(refs/users/meissner/heads/work058)] Add -msection-anchor-offset.

[gcc(refs/users/meissner/heads/work058)] Add -msection-anchor-offset.

[Michael Meissner]

https://gcc.gnu.org/g:78fc212da74885da1dad839d22811a4ddef4e60a

commit 78fc212da74885da1dad839d22811a4ddef4e60a
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Tue Jul 6 11:03:29 2021 -0400

    Add -msection-anchor-offset.
    
    This patch is part of a patch first posted in March, 2021, and it sets the
    minimum and maximum section anchor offsets.  The patch is at:
    https://gcc.gnu.org/pipermail/gcc-patches/2021-March/566744.html
    
    2021-07-06  Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
            * config/rs6000/rs6000.c (rs6000_option_override_internal) If
            -msection-anchor-offset, set the minimum and maximum section
            anchor offsets.
            * config/rs6000/rs6000.opt (-msection-anchor-offset): New switch.

Diff:
---
 gcc/config/rs6000/rs6000.c   | 11 +++++++++++
 gcc/config/rs6000/rs6000.opt |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index e127913a9ad..20a30727787 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -4550,6 +4550,17 @@ rs6000_option_override_internal (bool global_init_p)
   if (TARGET_CONST_ANCHOR)
     targetm.const_anchor = HOST_WIDE_INT_1 << (TARGET_PREFIXED ? 33 : 15);
 
+  /* Possibly set the minimum/maximum section anchor offset to the maximum
+     value, based on whether we have prefixed addressing.  */
+  if (TARGET_SECTION_ANCHOR_OFFSET)
+    {
+      HOST_WIDE_INT shift_amount = TARGET_PREFIXED ? 33 : 15;
+      targetm.min_anchor_offset = -(HOST_WIDE_INT_1 << shift_amount);
+      targetm.max_anchor_offset = (HOST_WIDE_INT_1 << shift_amount) - 1;
+      if (!global_options_set.x_flag_section_anchors)
+	flag_section_anchors = true;
+    }
+
   if (TARGET_DEBUG_REG || TARGET_DEBUG_TARGET)
     rs6000_print_isa_options (stderr, 0, "after subtarget", rs6000_isa_flags);
 
diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt
index 8ac78c369a4..a66d7a39938 100644
--- a/gcc/config/rs6000/rs6000.opt
+++ b/gcc/config/rs6000/rs6000.opt
@@ -644,6 +644,10 @@ mconst-anchor
 Target Undocumented Var(TARGET_CONST_ANCHOR) Save
 Set targetm.const_anchor
 
+msection-anchor-offset
+Target Undocumented Var(TARGET_SECTION_ANCHOR_OFFSET) Save
+Set targetm.{min,max}_anchor_offset
+
 mprefixed-large-consts
 Target Undocumented Var(TARGET_PREFIXED_LARGE_CONSTS) Init(-1) Save
 Generate (do not generate) PLI/SLDI/PADDI to load large constants.