[PATCH PR82096][gcc-7] Backport: Fix ICE in int_mode_for_mode, at stor-layout.c:403 with arm-linux-gnueabi

[Sudakshina Das]

Hi

This is a patch to backport r256526 and r256941 (Fix case fix) of trunk 
to fix emit_store_flag_force () function to fix the ICE. The original 
discussion is at 
https://gcc.gnu.org/ml/gcc-patches/2018-01/msg00219.html and 
https://gcc.gnu.org/ml/gcc-patches/2018-01/msg01058.html

Is this ok for gcc-7-branch?
Testing : Ran regression testing with bootstrapped arm-none-linux-gnueabihf.

Thanks
Sudi

ChangeLog entries:

*** gcc/ChangeLog ***

2018-01-22  Sudakshina Das  <sudi....@arm.com>

        Backport from mainline:
        2018-01-10  Sudakshina Das  <sudi....@arm.com>

        PR target/82096
        * expmed.c (emit_store_flag_force): Swap if const op0
        and change VOIDmode to mode of op0.

*** gcc/testsuite/ChangeLog ***

2018-01-22  Sudakshina Das  <sudi....@arm.com>

        Backport from mainline:
        2018-01-10  Sudakshina Das  <sudi....@arm.com>

        PR target/82096
        * gcc.c-torture/compile/pr82096.c: New test.
diff --git a/gcc/expmed.c b/gcc/expmed.c
index e9f634a..30001ac 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -5886,6 +5886,18 @@ emit_store_flag_force (rtx target, enum rtx_code code, rtx op0, rtx op1,
   if (tem != 0)
     return tem;
 
+  /* If one operand is constant, make it the second one.  Only do this
+     if the other operand is not constant as well.  */
+
+  if (swap_commutative_operands_p (op0, op1))
+    {
+      std::swap (op0, op1);
+      code = swap_condition (code);
+    }
+
+  if (mode == VOIDmode)
+    mode = GET_MODE (op0);
+
   if (!target)
     target = gen_reg_rtx (word_mode);
 
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr82096.c b/gcc/testsuite/gcc.c-torture/compile/pr82096.c
new file mode 100644
index 0000000..d144b70
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr82096.c
@@ -0,0 +1,11 @@
+/* { dg-require-effective-target arm_arch_v5t_ok { target arm*-*-* } } */
+/* { dg-skip-if "Do not combine float-abi values" { arm*-*-* } { "-mfloat-abi=*" } { "-mfloat-abi=soft" } } */
+/* { dg-additional-options "-march=armv5t -mthumb -mfloat-abi=soft" { target arm*-*-* } } */
+
+static long long AL[24];
+
+int
+check_ok (void)
+{
+  return (__sync_bool_compare_and_swap (AL+1, 0x200000003ll, 0x1234567890ll));
+}