[PATCH] arm: Fix ICE with CMSE nonsecure call on Armv8.1-M [PR100333]

[Alex Coplan via Gcc-patches]

Hi,

As the PR shows, we ICE shortly after expanding nonsecure calls for
Armv8.1-M.  For Armv8.1-M, we have TARGET_HAVE_FPCXT_CMSE. As it stands,
the expander (arm.md:nonsecure_call_internal) moves the callee's address
to a register (with copy_to_suggested_reg) only if
!TARGET_HAVE_FPCXT_CMSE.

However, looking at the pattern which the insn appears to be intended to
match (thumb2.md:*nonsecure_call_reg_thumb2_fpcxt), it requires the
callee's address to be in a register.

This patch therefore just forces the callee's address into a register in
the expander.

Testing:
 * Regtested an arm-eabi cross configured with
 --with-arch=armv8.1-m.main+mve.fp+fp.dp --with-float=hard. No regressions.
 * Bootstrap and regtest on arm-linux-gnueabihf in progress.

OK for trunk and backports as appropriate if bootstrap looks good?

Thanks,
Alex

gcc/ChangeLog:

        PR target/100333
        * config/arm/arm.md (nonsecure_call_internal): Always ensure
        callee's address is in a register.

gcc/testsuite/ChangeLog:

        PR target/100333
        * gcc.target/arm/cmse/pr100333.c: New test.

diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 45a471a887a..e2ad1a962e3 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -8580,18 +8580,21 @@ (define_expand "nonsecure_call_internal"
              (use (match_operand 2 "" ""))
              (clobber (reg:SI LR_REGNUM))])]
   "use_cmse"
-  "
   {
-    if (!TARGET_HAVE_FPCXT_CMSE)
-      {
-       rtx tmp =
-         copy_to_suggested_reg (XEXP (operands[0], 0),
-                                gen_rtx_REG (SImode, R4_REGNUM),
-                                SImode);
+    rtx tmp = NULL_RTX;
+    rtx addr = XEXP (operands[0], 0);
 
-       operands[0] = replace_equiv_address (operands[0], tmp);
-      }
-  }")
+    if (TARGET_HAVE_FPCXT_CMSE && !REG_P (addr))
+      tmp = force_reg (SImode, addr);
+    else if (!TARGET_HAVE_FPCXT_CMSE)
+      tmp = copy_to_suggested_reg (XEXP (operands[0], 0),
+                                  gen_rtx_REG (SImode, R4_REGNUM),
+                                  SImode);
+
+    if (tmp)
+      operands[0] = replace_equiv_address (operands[0], tmp);
+  }
+)
 
 (define_insn "*call_reg_armv5"
   [(call (mem:SI (match_operand:SI 0 "s_register_operand" "r"))
diff --git a/gcc/testsuite/gcc.target/arm/cmse/pr100333.c 
b/gcc/testsuite/gcc.target/arm/cmse/pr100333.c
new file mode 100644
index 00000000000..d8e3d809f73
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/cmse/pr100333.c
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-mcmse" } */
+typedef void __attribute__((cmse_nonsecure_call)) t(void);
+t g;
+void f() {
+  g();
+}