diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1b246171d468..430aedbcb052 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2019-12-03  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gimplify.c (gimplify_compound_lval): Don't gimplify and install
+	an array element size if array_element_size is already an invariant.
+	Similarly don't gimplify and install a field offset if
+	component_ref_field_offset is already an invariant.
+
 2019-12-03  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* cfgexpand.c (discover_nonconstant_array_refs_r): If an access
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index da6566903e07..9073680cb317 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -2987,17 +2987,18 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
 
 	  if (TREE_OPERAND (t, 3) == NULL_TREE)
 	    {
-	      tree elmt_type = TREE_TYPE (TREE_TYPE (TREE_OPERAND (t, 0)));
-	      tree elmt_size = unshare_expr (array_ref_element_size (t));
-	      tree factor = size_int (TYPE_ALIGN_UNIT (elmt_type));
-
-	      /* Divide the element size by the alignment of the element
-		 type (above).  */
-	      elmt_size
-		= size_binop_loc (loc, EXACT_DIV_EXPR, elmt_size, factor);
-
+	      tree elmt_size = array_ref_element_size (t);
 	      if (!is_gimple_min_invariant (elmt_size))
 		{
+		  elmt_size = unshare_expr (elmt_size);
+		  tree elmt_type = TREE_TYPE (TREE_TYPE (TREE_OPERAND (t, 0)));
+		  tree factor = size_int (TYPE_ALIGN_UNIT (elmt_type));
+
+		  /* Divide the element size by the alignment of the element
+		     type (above).  */
+		  elmt_size = size_binop_loc (loc, EXACT_DIV_EXPR,
+					      elmt_size, factor);
+
 		  TREE_OPERAND (t, 3) = elmt_size;
 		  tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p,
 					post_p, is_gimple_reg,
@@ -3017,16 +3018,18 @@ gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
 	  /* Set the field offset into T and gimplify it.  */
 	  if (TREE_OPERAND (t, 2) == NULL_TREE)
 	    {
-	      tree offset = unshare_expr (component_ref_field_offset (t));
-	      tree field = TREE_OPERAND (t, 1);
-	      tree factor
-		= size_int (DECL_OFFSET_ALIGN (field) / BITS_PER_UNIT);
-
-	      /* Divide the offset by its alignment.  */
-	      offset = size_binop_loc (loc, EXACT_DIV_EXPR, offset, factor);
-
+	      tree offset = component_ref_field_offset (t);
 	      if (!is_gimple_min_invariant (offset))
 		{
+		  offset = unshare_expr (offset);
+		  tree field = TREE_OPERAND (t, 1);
+		  tree factor
+		    = size_int (DECL_OFFSET_ALIGN (field) / BITS_PER_UNIT);
+
+		  /* Divide the offset by its alignment.  */
+		  offset = size_binop_loc (loc, EXACT_DIV_EXPR,
+					   offset, factor);
+
 		  TREE_OPERAND (t, 2) = offset;
 		  tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p,
 					post_p, is_gimple_reg,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 028755bb51a8..39e8ace59f79 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2019-12-03  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.target/aarch64/sve/acle/general-c/struct_1.c: New test.
+
 2019-12-03  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* gcc.target/aarch64/sve/acle/general/deref_1.c: New test.
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/struct_1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/struct_1.c
new file mode 100644
index 000000000000..1ebc229250eb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/struct_1.c
@@ -0,0 +1,10 @@
+/* { dg-options "-std=c99" } */
+
+#include <arm_sve.h>
+
+void
+f (svint8_t a, svint8_t b)
+{
+  /* Not supported, but mustn't ICE.  */
+  (svint8x2_t) { a, b };
+}