vregs: Fix up instantiate_virtual_regs_in_insn for asm goto with outputs [PR98603]

If an asm insn fails constraint checking during vregs, it is just deleted.
We don't delete asm goto though because of the edges to the labels, so
instantiate_virtual_regs_in_insn would just remove the inputs and their
constraints, the pattern etc.
This worked fine when asm goto couldn't have output operands, but causes
ICEs later on when it has more than one output (and furthermore doesn't
really remove the problematic outputs).  The problem is that
for multiple outputs we have a PARALLEL with multiple ASM_OPERANDS, but
those must use the same ASM_OPERANDS_INPUT_VEC etc., but the code was
adjusting just one.

The following patch turns invalid asm goto into a bare
asm goto ("" : : : : lab, lab2, lab3);
i.e. no inputs/outputs/clobbers, just the labels.

2021-01-09  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/98603
	* function.c (instantiate_virtual_regs_in_insn): For asm goto
	with impossible constraints, drop all SETs, CLOBBERs, drop PARALLEL
	if any, set ASM_OPERANDS mode to VOIDmode and change
	ASM_OPERANDS_OUTPUT_CONSTRAINT and ASM_OPERANDS_OUTPUT_IDX.

	* gcc.target/i386/pr98603.c: New test.
	* gcc.target/aarch64/pr98603.c: New test.

diff --git a/gcc/function.c b/gcc/function.c
index 4b9c0a5aa1971ccd8bc2d2ba99a1e703ad4180d7..a3ed3987b9523eb2fdc75986bb992e9fb15c2509 100644 (file)
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -1785,12 +1785,16 @@ instantiate_virtual_regs_in_insn (rtx_insn *insn)
        {
          error_for_asm (insn, "impossible constraint in %<asm%>");
          /* For asm goto, instead of fixing up all the edges
-            just clear the template and clear input operands
-            (asm goto doesn't have any output operands).  */
+            just clear the template and clear input and output operands
+            and strip away clobbers.  */
          if (JUMP_P (insn))
            {
              rtx asm_op = extract_asm_operands (PATTERN (insn));
+             PATTERN (insn) = asm_op;
+             PUT_MODE (asm_op, VOIDmode);
              ASM_OPERANDS_TEMPLATE (asm_op) = ggc_strdup ("");
+             ASM_OPERANDS_OUTPUT_CONSTRAINT (asm_op) = "";
+             ASM_OPERANDS_OUTPUT_IDX (asm_op) = 0;
              ASM_OPERANDS_INPUT_VEC (asm_op) = rtvec_alloc (0);
              ASM_OPERANDS_INPUT_CONSTRAINT_VEC (asm_op) = rtvec_alloc (0);
            }

diff --git a/gcc/testsuite/gcc.target/aarch64/pr98603.c b/gcc/testsuite/gcc.target/aarch64/pr98603.c
new file mode 100644 (file)
index 0000000..f75d8e4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr98603.c
@@ -0,0 +1,11 @@
+/* PR rtl-optimization/98603 */
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+
+int
+foo (void)
+{
+  int b, c;
+  asm goto ("" : "=R" (b), "=r" (c) : : : lab);        /* { dg-error "impossible constraint in 'asm'" } */
+lab:;
+}

diff --git a/gcc/testsuite/gcc.target/i386/pr98603.c b/gcc/testsuite/gcc.target/i386/pr98603.c
new file mode 100644 (file)
index 0000000..9bf924e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr98603.c
@@ -0,0 +1,11 @@
+/* PR rtl-optimization/98603 */
+/* { dg-do compile } */
+/* { dg-options "-O0 -w" } */
+
+int
+foo (void)
+{
+  int b, c;
+  asm goto ("" : "=r" (b), "=r" (c) : "I" (128) : : lab);      /* { dg-error "impossible constraint in 'asm'" } */
+lab:;
+}