Fix output_constructor_bitfield handling of wide bitfields (PR89037)

The testcase was failing because we were trying to access
TREE_INT_CST_ELT (x, 1) of a 128-bit integer that was small enough
to need only a single element.

2019-01-25  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	PR middle-end/89037
	* varasm.c (output_constructor_bitfield): Use wi::extract_uhwi
	instead of accessing TREE_INT_CST_ELT directly.

gcc/testsuite/
	PR middle-end/89037
	* gcc.dg/pr89037.c: New test.

From-SVN: r268272

4 files changed, 44 insertions, 13 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a3464e0..2f7731a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-25  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR middle-end/89037
+	* varasm.c (output_constructor_bitfield): Use wi::extract_uhwi
+	instead of accessing TREE_INT_CST_ELT directly.
+
 2019-01-25  Christophe Lyon  <christophe.lyon@linaro.org>
 
 	* doc/sourcebuild.texi (Environment attributes): Add fenv and
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 10536c9..29d6426 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-01-25  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR middle-end/89037
+	* gcc.dg/pr89037.c: New test.
+
 2019-01-25  Christophe Lyon  <christophe.lyon@linaro.org>
 
 	* lib/target-supports.exp (check_effective_target_fenv): New.
diff --git a/gcc/testsuite/gcc.dg/pr89037.c b/gcc/testsuite/gcc.dg/pr89037.c
new file mode 100644
index 0000000..5511367
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr89037.c
@@ -0,0 +1,24 @@
+/* { dg-do run { target int128 } } */
+/* { dg-options "" } */
+
+struct s
+{
+  __int128 y : 66;
+};
+typedef struct s T;
+T a[] = { 1, 10000, 0x12345, 0xff000001, 1ULL << 63, (__int128) 1 << 64,
+	  ((__int128) 1 << 64) | 1 };
+
+int
+main (void)
+{
+  if (a[0].y != 1
+      || a[1].y != 10000
+      || a[2].y != 0x12345
+      || a[3].y != 0xff000001
+      || a[4].y != (1ULL << 63)
+      || a[5].y != ((__int128) 1 << 64)
+      || a[6].y != (((__int128) 1 << 64) | 1))
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/varasm.c b/gcc/varasm.c
index bddd3d2..0be44f1 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -5349,7 +5349,7 @@ output_constructor_bitfield (oc_local_state *local, unsigned int bit_offset)
     {
       int this_time;
       int shift;
-      HOST_WIDE_INT value;
+      unsigned HOST_WIDE_INT value;
       HOST_WIDE_INT next_byte = next_offset / BITS_PER_UNIT;
       HOST_WIDE_INT next_bit = next_offset % BITS_PER_UNIT;
 
@@ -5381,15 +5381,13 @@ output_constructor_bitfield (oc_local_state *local, unsigned int bit_offset)
 	      this_time = end - shift + 1;
 	    }
 
-	  /* Now get the bits from the appropriate constant word.  */
-	  value = TREE_INT_CST_ELT (local->val, shift / HOST_BITS_PER_WIDE_INT);
-	  shift = shift & (HOST_BITS_PER_WIDE_INT - 1);
+	  /* Now get the bits we want to insert.  */
+	  value = wi::extract_uhwi (wi::to_widest (local->val),
+				    shift, this_time);
 
 	  /* Get the result.  This works only when:
 	     1 <= this_time <= HOST_BITS_PER_WIDE_INT.  */
-	  local->byte |= (((value >> shift)
-			   & (((HOST_WIDE_INT) 2 << (this_time - 1)) - 1))
-			  << (BITS_PER_UNIT - this_time - next_bit));
+	  local->byte |= value << (BITS_PER_UNIT - this_time - next_bit);
 	}
       else
 	{
@@ -5406,15 +5404,13 @@ output_constructor_bitfield (oc_local_state *local, unsigned int bit_offset)
 	    this_time
 	      = HOST_BITS_PER_WIDE_INT - (shift & (HOST_BITS_PER_WIDE_INT - 1));
 
-	  /* Now get the bits from the appropriate constant word.  */
-	  value = TREE_INT_CST_ELT (local->val, shift / HOST_BITS_PER_WIDE_INT);
-	  shift = shift & (HOST_BITS_PER_WIDE_INT - 1);
+	  /* Now get the bits we want to insert.  */
+	  value = wi::extract_uhwi (wi::to_widest (local->val),
+				    shift, this_time);
 
 	  /* Get the result.  This works only when:
 	     1 <= this_time <= HOST_BITS_PER_WIDE_INT.  */
-	  local->byte |= (((value >> shift)
-			   & (((HOST_WIDE_INT) 2 << (this_time - 1)) - 1))
-			  << next_bit);
+	  local->byte |= value << next_bit;
 	}
 
       next_offset += this_time;