explow: Fix ICE caused by plus_constant [PR94002]

The following testcase ICEs in cross to riscv64-linux.  The problem is
that we have a DImode integral constant (that doesn't fit into SImode),
which is pushed into a constant pool and later access just the first half of
it using a MEM.  When plus_constant is called on such a MEM, if the constant
has mode, we verify the mode, but if it doesn't, we don't and ICE later on
when we think the CONST_INT is a valid SImode constant.

2020-03-03  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/94002
	* explow.c (plus_constant): Punt if cst has VOIDmode and
	get_pool_mode is different from mode.

	* gcc.dg/pr94002.c: New test.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 29321726b9df9502b3a34e260379ede5ed2f49cd..640d64180f8ac40c09df63817be08ad1bbcecceb 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-03-03  Jakub Jelinek  <jakub@redhat.com>
+
+       PR rtl-optimization/94002
+       * explow.c (plus_constant): Punt if cst has VOIDmode and
+       get_pool_mode is different from mode.
+
 2020-03-02  Jason Merrill  <jason@redhat.com>
 
        PR c++/92601

diff --git a/gcc/explow.c b/gcc/explow.c
index aea7118af1e2556126387ac62789044050e69565..ea22ecf0939a19b4fa59ef91e63b0c84b608fef3 100644 (file)
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -128,6 +128,9 @@ plus_constant (machine_mode mode, rtx x, poly_int64 c, bool inplace)
              cst = gen_lowpart (mode, cst);
              gcc_assert (cst);
            }
+         else if (GET_MODE (cst) == VOIDmode
+                  && get_pool_mode (XEXP (x, 0)) != mode)
+           break;
          if (GET_MODE (cst) == VOIDmode || GET_MODE (cst) == mode)
            {
              tem = plus_constant (mode, cst, c);

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 821f91c7c1302be365e28fc173c839cea3d65d35..dc562bc4c8a7b99b6cd50cab1103a536afc235a6 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-03  Jakub Jelinek  <jakub@redhat.com>
+
+       PR rtl-optimization/94002
+       * gcc.dg/pr94002.c: New test.
+
 2020-02-29  Peter Bergner  <bergner@linux.ibm.com>
 
        Revert

diff --git a/gcc/testsuite/gcc.dg/pr94002.c b/gcc/testsuite/gcc.dg/pr94002.c
new file mode 100644 (file)
index 0000000..05a02f3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94002.c
@@ -0,0 +1,13 @@
+/* PR rtl-optimization/94002 */
+/* { dg-do compile } */
+/* { dg-options "-O1 -fno-tree-dce -fno-tree-reassoc" } */
+/* { dg-additional-options "-fPIC" { target fpic } } */
+
+unsigned a, b;
+
+void
+foo (void)
+{
+  __builtin_sub_overflow (b, 44852956282LL, &a);
+  a += ~b;
+}