https://gcc.gnu.org/g:ea7962211ffa96fc13cf8eba60c396a3cf9dfd97
commit ea7962211ffa96fc13cf8eba60c396a3cf9dfd97
Author: Michael Meissner <meiss...@linux.ibm.com>
Date: Mon Jun 16 19:30:47 2025 -0400
PR target/120681 - allow -mcmodel=large with prefixed addressing
When I implemented the pc-relative support for power10 in GCC, I disabled
using
pc-relative support for -mcmodel=large. At the time, I didn't want to dig
into
the issues. It is now time to allow -mcmodel=large to generate pc-relative
code.
This patch allows -mcmodel=large to use prefixed addressing on power10,
power11,
and possibly other future PowerPC processors.
This patch deletes the code that disallows -mprefixed and -mcmodel=large.
By
deleting the code, it allows the normal pc-relative addressing to be used.
For
static variables, pc-relative addressing will be used. For external
variables,
we will generate the normal code that uses '@got@pcrel' addressing to load
up
the external address and use this address as a pointer to do the load or
store.
2025-06-16 Michael Meissner <meiss...@linux.ibm.com>
gcc/
PR target/120681
* config/rs6000/rs6000.cc (rs6000_option_override_internal): Delete
code
that forced using TOC addressing for -mcmodel=large instead of
pc-relative addressing.
gcc/testsuite/
PR target/120681
* gcc.target/powerpc/pr120681.c: New test.
Diff:
---
gcc/config/rs6000/rs6000.cc | 10 ----------
gcc/testsuite/gcc.target/powerpc/pr120681.c | 31 +++++++++++++++++++++++++++++
2 files changed, 31 insertions(+), 10 deletions(-)
diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 80fc500fcec8..a268e0d17b5f 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -4360,16 +4360,6 @@ rs6000_option_override_internal (bool global_init_p)
&& (rs6000_isa_flags_explicit & OPTION_MASK_PCREL) == 0)
rs6000_isa_flags |= OPTION_MASK_PCREL;
- /* -mpcrel requires -mcmodel=medium, but we can't check TARGET_CMODEL until
- after the subtarget override options are done. */
- else 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;
- }
-
/* Enable -mmma by default on power10 systems. */
if (TARGET_POWER10 && (rs6000_isa_flags_explicit & OPTION_MASK_MMA) == 0)
rs6000_isa_flags |= OPTION_MASK_MMA;
diff --git a/gcc/testsuite/gcc.target/powerpc/pr120681.c
b/gcc/testsuite/gcc.target/powerpc/pr120681.c
new file mode 100644
index 000000000000..ad0bd64ceeaf
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr120681.c
@@ -0,0 +1,31 @@
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2 -mcmodel=large" } */
+
+/* PR target/120681 -- verify that -mcpu=power10 -mcmodel=large uses prefixed
+ addressing instead of forcing using TOC addressing. */
+
+#ifndef TYPE
+#define TYPE unsigned long
+#endif
+
+extern TYPE global_var;
+
+void
+set_global (TYPE value)
+{
+ /*
+ * Generate:
+ * pld 9,global_var@got@pcrel
+ * std 3,0(9)
+ *
+ * Not:
+ * addis 9,2,.LC0@toc@ha
+ * ld 9,.LC0@toc@l(9)
+ * std 3,0(9)
+ */
+
+ global_var = value;
+}
+
+/* { dg-final { scan-assembler {@got@pcrel} } } */
+/* { dg-final { scan-assembler-not {@toc} } } */
