[gcc r14-10716] x86: Don't use address override with segment regsiter

[H.J. Lu]

https://gcc.gnu.org/g:25cb153f93bb9ff3543ba8e31bbe7be4f6168aa4

commit r14-10716-g25cb153f93bb9ff3543ba8e31bbe7be4f6168aa4
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Sep 25 16:39:04 2024 +0800

    x86: Don't use address override with segment regsiter
    
    Address override only applies to the (reg32) part in the thread address
    fs:(reg32).  Don't rewrite thread address like
    
    (set (reg:CCZ 17 flags)
        (compare:CCZ (reg:SI 98 [ __gmpfr_emax.0_1 ])
            (mem/c:SI (plus:SI (plus:SI (unspec:SI [
                                (const_int 0 [0])
                            ] UNSPEC_TP)
                        (reg:SI 107))
                    (const:SI (unspec:SI [
                                (symbol_ref:SI ("previous_emax") [flags 0x1a] <var_decl 0x7fffe9a11cf0 previous_emax>)
                            ] UNSPEC_DTPOFF))) [1 previous_emax+0 S4 A32])))
    
    if address override is used to avoid the invalid memory operand like
    
            cmpl    %fs:previous_emax@dtpoff(%eax), %r12d
    
    gcc/
    
            PR target/116839
            * config/i386/i386.cc (ix86_rewrite_tls_address_1): Make it
            static.  Return if TLS address is thread register plus an integer
            register.
    
    gcc/testsuite/
    
            PR target/116839
            * gcc.target/i386/pr116839.c: New file.
    
    Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
    (cherry picked from commit c79cc30862d7255ca15884aa956d1ccfa279d86a)

Diff:
---
 gcc/config/i386/i386.cc                  |  9 +++++-
 gcc/testsuite/gcc.target/i386/pr116839.c | 48 ++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 8f1c1f9ccd0a..93d05a301c92 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -12458,7 +12458,7 @@ ix86_tls_address_pattern_p (rtx op)
 }
 
 /* Rewrite *LOC so that it refers to a default TLS address space.  */
-void
+static void
 ix86_rewrite_tls_address_1 (rtx *loc)
 {
   subrtx_ptr_iterator::array_type array;
@@ -12480,6 +12480,13 @@ ix86_rewrite_tls_address_1 (rtx *loc)
 		  if (GET_CODE (u) == UNSPEC
 		      && XINT (u, 1) == UNSPEC_TP)
 		    {
+		      /* NB: Since address override only applies to the
+			 (reg32) part in fs:(reg32), return if address
+			 override is used.  */
+		      if (Pmode != word_mode
+			  && REG_P (XEXP (*x, 1 - i)))
+			return;
+
 		      addr_space_t as = DEFAULT_TLS_SEG_REG;
 
 		      *x = XEXP (*x, 1 - i);
diff --git a/gcc/testsuite/gcc.target/i386/pr116839.c b/gcc/testsuite/gcc.target/i386/pr116839.c
new file mode 100644
index 000000000000..e5df82562518
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr116839.c
@@ -0,0 +1,48 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-require-effective-target maybe_x32 } */
+/* { dg-options "-mx32 -O2 -fPIC -mtls-dialect=gnu2" } */
+/* { dg-final { scan-assembler-not "cmpl\[ \t\]+%fs:previous_emax@dtpoff\\(%eax\\)" } } */
+
+typedef long mpfr_prec_t;
+typedef long mpfr_exp_t;
+typedef struct {
+  mpfr_prec_t _mpfr_prec;
+} __mpfr_struct;
+typedef __mpfr_struct mpfr_t[1];
+extern _Thread_local mpfr_exp_t __gmpfr_emax;
+static _Thread_local mpfr_exp_t previous_emax;
+static _Thread_local mpfr_t bound_emax;
+extern const mpfr_t __gmpfr_const_log2_RNDD;
+extern const mpfr_t __gmpfr_const_log2_RNDU;
+
+typedef enum {
+  MPFR_RNDN=0,
+  MPFR_RNDZ,
+  MPFR_RNDU,
+  MPFR_RNDD,
+  MPFR_RNDA,
+  MPFR_RNDF,
+  MPFR_RNDNA=-1
+} mpfr_rnd_t;
+typedef __mpfr_struct *mpfr_ptr;
+typedef const __mpfr_struct *mpfr_srcptr;
+void mpfr_mul (mpfr_ptr, mpfr_srcptr, mpfr_rnd_t);
+
+void
+foo (void)
+{
+  mpfr_exp_t saved_emax;
+
+  if (__gmpfr_emax != previous_emax)
+    {
+      saved_emax = __gmpfr_emax;
+
+      bound_emax->_mpfr_prec = 32;
+
+      mpfr_mul (bound_emax, saved_emax < 0 ?
+                __gmpfr_const_log2_RNDD : __gmpfr_const_log2_RNDU,
+                MPFR_RNDU);
+      previous_emax = saved_emax;
+      __gmpfr_emax = saved_emax;
+    }
+}