PR c/88000 - Different local vars regs order may produce different code

gcc/c/ChangeLog:

	PR c/88000
	* c-typeck.c (convert_arguments):  Call warn_hw_reg_arg to diagnose
	unsupported uses of hardware register variables.

gcc/c-family/ChangeLog:

	PR c/88000
	* c.opt (-Wasm-register-var): New option.
	* c-common.h (warn_hw_reg_arg): Declare.
	* c-warn.c (warn_hw_reg_arg): Define.

gcc/cp/ChangeLog:

	PR c/88000
	* call.c (build_over_call): Call warn_hw_reg_arg.

gcc/testsuite/ChangeLog:

	PR c/88000
	* c-c++-common/Wasm-register.c: New test.
	* g++.dg/ext/Wasm-register.C: Same.
	* gcc.dg/torture/pr71762-3.c: Prune excess diagnostics.
	* gcc.target/i386/attr-returns_twice-1.c: Same.
	* gcc.target/i386/avx512dq-abs-copysign-1.c: Same.
	* gcc.target/i386/avx512dq-concatv2si-1.c: Same.
	* gcc.target/i386/avx512vl-abs-copysign-1.c: Same.
	* gcc.target/i386/avx512vl-abs-copysign-2.c: Same.
	* gcc.target/i386/avx512vl-concatv2si-1.c: Same.

gcc/ChangeLog:

	PR c/88000
	* doc/invoke.texi (-Wasm-register-var): Document.

Index: gcc/c/c-typeck.c
===================================================================
--- gcc/c/c-typeck.c	(revision 266086)
+++ gcc/c/c-typeck.c	(working copy)
@@ -3543,6 +3543,9 @@ convert_arguments (location_t loc, vec<location_t>
 	/* Convert `short' and `char' to full-size `int'.  */
 	parmval = default_conversion (val);
 
+      /* Diagnose uses of local variables declared asm register.  */
+      warn_hw_reg_arg (fundecl, parmnum + 1, val);
+
       (*values)[parmnum] = parmval;
       if (parmval == error_mark_node)
 	error_args = true;
Index: gcc/c-family/c.opt
===================================================================
--- gcc/c-family/c.opt	(revision 266086)
+++ gcc/c-family/c.opt	(working copy)
@@ -338,6 +338,10 @@ Warray-bounds=
 LangEnabledBy(C ObjC C++ LTO ObjC++,Wall,1,0)
 ; in common.opt
 
+Wasm-register-var
+C ObjC C++ ObjC++ Var(warn_asm_register_var) Warning Init(1)
+Warn for unsupported uses of variables declared asm register.
+
 Wassign-intercept
 ObjC ObjC++ Var(warn_assign_intercept) Warning
 Warn whenever an Objective-C assignment is being intercepted by the garbage collector.
Index: gcc/c-family/c-common.h
===================================================================
--- gcc/c-family/c-common.h	(revision 266086)
+++ gcc/c-family/c-common.h	(working copy)
@@ -1321,6 +1321,7 @@ extern bool diagnose_mismatched_attributes (tree,
 extern tree do_warn_duplicated_branches_r (tree *, int *, void *);
 extern void warn_for_multistatement_macros (location_t, location_t,
 					    location_t, enum rid);
+extern void warn_hw_reg_arg (tree, int, tree);
 
 /* In c-attribs.c.  */
 extern bool attribute_takes_identifier_p (const_tree);
Index: gcc/c-family/c-warn.c
===================================================================
--- gcc/c-family/c-warn.c	(revision 266086)
+++ gcc/c-family/c-warn.c	(working copy)
@@ -2609,3 +2609,39 @@ warn_for_multistatement_macros (location_t body_lo
     inform (guard_loc, "some parts of macro expansion are not guarded by "
 	    "this %qs clause", guard_tinfo_to_string (keyword));
 }
+
+
+/* Diagnose unsuported use of explicit hardware register variable ARG
+   as an argument ARGNO to function FNDECL.  */
+
+void
+warn_hw_reg_arg (tree fndecl, int argno, tree arg)
+{
+  if (!fndecl)
+    return;
+
+  /* Avoid diagnosing GCC intrinsics with no library fallbacks.  */
+  if (fndecl_built_in_p (fndecl)
+      && DECL_IS_BUILTIN (fndecl)
+      && !c_decl_implicit (fndecl)
+      && !DECL_ASSEMBLER_NAME_SET_P (fndecl))
+    return;
+
+  /* Also avoid diagnosing always_inline functions since those are
+     often used to implement vectorization intrinsics that make use
+     of hardware register variables.  */
+  if (lookup_attribute ("always_inline", DECL_ATTRIBUTES (fndecl)))
+    return;
+
+  /* Diagnose uses of local variables declared asm register.  */
+  STRIP_ANY_LOCATION_WRAPPER (arg);
+  if (VAR_P (arg)
+      && !TREE_STATIC (arg)
+      && DECL_HARD_REGISTER (arg)
+      && warning_at (input_location, OPT_Wasm_register_var,
+		     "unsupported use of hardware register %qD as "
+		     "argument %d of %qD",
+		     arg, argno, fndecl))
+    inform (DECL_SOURCE_LOCATION (arg),
+	    "%qD declared here", arg);
+}
Index: gcc/cp/call.c
===================================================================
--- gcc/cp/call.c	(revision 266086)
+++ gcc/cp/call.c	(working copy)
@@ -8111,6 +8111,9 @@ build_over_call (struct z_candidate *cand, int fla
 
       conv = convs[i];
 
+      /* Diagnose uses of local variables declared asm register.  */
+      warn_hw_reg_arg (cand->fn, i + 1, arg);
+
       /* If the argument is NULL and used to (implicitly) instantiate a
          template function (and bind one of the template arguments to
          the type of 'long int'), we don't want to warn about passing NULL
@@ -8207,6 +8210,9 @@ build_over_call (struct z_candidate *cand, int fla
   for (; arg_index < vec_safe_length (args); ++arg_index)
     {
       tree a = (*args)[arg_index];
+      /* Diagnose uses of local variables declared asm register.  */
+      warn_hw_reg_arg (cand->fn, arg_index + 1, a);
+
       if ((magic == 3 && arg_index == 2) || magic == 2)
 	{
 	  /* Do no conversions for certain magic varargs.  */
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 266086)
+++ gcc/doc/invoke.texi	(working copy)
@@ -283,6 +283,7 @@ Objective-C and Objective-C++ Dialects}.
 -Walloc-zero  -Walloc-size-larger-than=@var{byte-size}
 -Walloca  -Walloca-larger-than=@var{byte-size} @gol
 -Wno-aggressive-loop-optimizations  -Warray-bounds  -Warray-bounds=@var{n} @gol
+-Wasm-register-var @gol
 -Wno-attributes -Wno-attribute-alias @gol
 -Wbool-compare  -Wbool-operation @gol
 -Wno-builtin-declaration-mismatch @gol
@@ -5868,6 +5869,13 @@ pointers. This warning level may give a larger num
 false positives and is deactivated by default.
 @end table
 
+@item -Wno-asm-register-var
+@opindex Wasm-register-var
+@opindex Wno-asm-register-var
+Warn about unsupported uses of hardware register variables, or those declared
+using the @code{asm register} extension (@pxref{Explicit Register Variables}).
+This warning is enabled by default.
+
 @item -Wattribute-alias=@var{n}
 @itemx -Wno-attribute-alias
 @opindex -Wattribute-alias
Index: gcc/testsuite/c-c++-common/Wasm-register.c
===================================================================
--- gcc/testsuite/c-c++-common/Wasm-register.c	(nonexistent)
+++ gcc/testsuite/c-c++-common/Wasm-register.c	(working copy)
@@ -0,0 +1,120 @@
+/* PR 88000 - Different local vars regs order may produce different code
+   Verify that passing asm register variables as arguments to functions
+   triggers a warning.
+   { dg-do compile }
+   { dg-options "-Wno-pedantic" } */
+
+#if __cplusplus
+/* Fake C++ function without a prototype.  */
+void fany (...);
+#else
+void fany ();
+#endif
+
+void fproto (char, int);
+void fellip (int, ...);
+
+register char gcr __asm__ ("r12");
+register long glr __asm__ ("r13");
+
+
+void test_global_no_proto (void)
+{
+  fany (gcr);
+  fany (0, gcr);
+  fany (glr);
+  fany (0, glr);
+}
+
+
+/* Verify that calls to a GCC intrinsic with no library fallback do
+   not trigger a warning.  */
+
+void test_gcc_builtin (void)
+{
+  register char cr __asm__ ("r11") = 1;
+  register int ir __asm__ ("r12") = 22;
+
+  __builtin_clz (cr);
+  __builtin_clz (ir);
+}
+
+
+/* Verify that calls to a GCC intrinsic with a library fallback do
+   trigger a warning.  */
+
+void test_lib_builtin (void)
+{
+  register char cr __asm__ ("r11") = 1;
+  register int ir __asm__ ("r12") = 22;
+
+  __builtin_abs (cr);     /* { dg-warning "unsupported use of hardware register .cr. as argument 1 of .\(int \)?__builtin_abs" } */
+
+  __builtin_abs (ir);     /* { dg-warning "unsupported use of hardware register .ir. as argument 1 " } */
+}
+
+
+void test_local_no_proto (void)
+{
+  register char cr __asm__ ("r11") = 1;
+  register int ir __asm__ ("r12") = 22;
+
+  fany (cr);          /* { dg-warning "unsupported use of hardware register .cr. as argument 1 of .\(void \)?fany" } */
+
+  fany (0, cr);       /* { dg-warning "unsupported use of hardware register .cr. as argument 2 " } */
+
+  fany (ir);          /* { dg-warning "unsupported use of hardware register .ir. as argument 1 " } */
+
+  fany (0, ir);       /* { dg-warning "unsupported use of hardware register .ir. as argument 2 " } */
+}
+
+
+void test_global_proto (void)
+{
+  fproto (gcr, 0);
+  fproto (0, gcr);
+  fproto (glr, 0);
+  fproto (0, glr);
+}
+
+
+void test_local_proto (void)
+{
+  register char cr __asm__ ("r11") = 1;
+  register int ir __asm__ ("r12") = 22;
+
+  fproto (cr, 0);     /* { dg-warning "unsupported use of hardware register .cr. as argument 1 of .\(void \)?fproto" } */
+
+  fproto (0, cr);     /* { dg-warning "unsupported use of hardware register .cr. as argument 2 " } */
+
+  fproto (ir, 0);     /* { dg-warning "unsupported use of hardware register .ir. as argument 1 " } */
+
+  fproto (0, ir);     /* { dg-warning "unsupported use of hardware register .ir. as argument 2 " } */
+}
+
+
+void test_global_ellip (void)
+{
+  fellip (gcr);
+  fellip (glr);
+  fellip (0, gcr);
+  fellip (0, glr);
+}
+
+
+void test_local_ellip (void)
+{
+  register char cr __asm__ ("r11") = 1;
+  register int ir __asm__ ("r12") = 22;
+
+  fellip (cr);        /* { dg-warning "unsupported use of hardware register .cr. as argument 1 of .\(void \)?fellip." } */
+
+  fellip (ir);        /* { dg-warning "unsupported use of hardware register .ir. as argument 1 " } */
+
+  fellip (0, cr);     /* { dg-warning "unsupported use of hardware register .cr. as argument 2 " } */
+
+  fellip (0, ir);     /* { dg-warning "unsupported use of hardware register .ir. as argument 2 " } */
+}
+
+
+/* { dg-prune-output "register used" } */
Index: gcc/testsuite/g++.dg/ext/Wasm-register.C
===================================================================
--- gcc/testsuite/g++.dg/ext/Wasm-register.C	(nonexistent)
+++ gcc/testsuite/g++.dg/ext/Wasm-register.C	(working copy)
@@ -0,0 +1,31 @@
+/* PR c/88000 - Different local vars regs order may produce different code
+   Verify that passing asm register variables as arguments to a function
+   template triggers a warning.
+   { dg-do compile }
+   { dg-options "-Wno-pedantic" } */
+
+template <class T>
+void f (T);
+
+register char gcr __asm__ ("r12");
+register long glr __asm__ ("r13");
+
+
+void test_global (void)
+{
+  f (gcr);
+  f (glr);
+}
+
+
+void test_local (void)
+{
+  register char cr __asm__ ("r11") = 1;
+  register int ir __asm__ ("r12") = 22;
+
+  f (cr);          /* { dg-warning "unsupported use of hardware register .cr. as argument 1 of .void f\\\(T\\\) \\\[with T = char]" } */
+
+  f (ir);          /* { dg-warning "unsupported use of hardware register .ir. as argument 1 of .void f\\\(T\\\) \\\[with T = int]" } */
+}
+
+/* { dg-prune-output "register used" } */
Index: gcc/testsuite/gcc.dg/torture/pr71762-3.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr71762-3.c	(revision 266086)
+++ gcc/testsuite/gcc.dg/torture/pr71762-3.c	(working copy)
@@ -20,3 +20,5 @@ int main()
     __builtin_abort ();
   return 0;
 }
+
+/* { dg-prune-output "unsupported use of hardware register" } */
Index: gcc/testsuite/gcc.target/i386/attr-returns_twice-1.c
===================================================================
--- gcc/testsuite/gcc.target/i386/attr-returns_twice-1.c	(revision 266086)
+++ gcc/testsuite/gcc.target/i386/attr-returns_twice-1.c	(working copy)
@@ -21,3 +21,5 @@ main (void)
 
   return 0;
 }
+
+/* { dg-prune-output "unsupported use of hardware register" } */
Index: gcc/testsuite/gcc.target/i386/avx512dq-abs-copysign-1.c
===================================================================
--- gcc/testsuite/gcc.target/i386/avx512dq-abs-copysign-1.c	(revision 266086)
+++ gcc/testsuite/gcc.target/i386/avx512dq-abs-copysign-1.c	(working copy)
@@ -69,3 +69,4 @@ f6 (double x)
 /* { dg-final { scan-assembler "vandpd\[^\n\r\]*xmm18" } } */
 /* { dg-final { scan-assembler "vorpd\[^\n\r\]*xmm18" } } */
 /* { dg-final { scan-assembler "vxorpd\[^\n\r\]*xmm18" } } */
+/* { dg-prune-output "unsupported use of hardware register" } */
Index: gcc/testsuite/gcc.target/i386/avx512dq-concatv2si-1.c
===================================================================
--- gcc/testsuite/gcc.target/i386/avx512dq-concatv2si-1.c	(revision 266086)
+++ gcc/testsuite/gcc.target/i386/avx512dq-concatv2si-1.c	(working copy)
@@ -41,3 +41,4 @@ f3 (int x, int *y)
 }
 
 /* { dg-final { scan-assembler-times "vpinsrd\[^\n\r]*\\\$1\[^\n\r]*%xmm16\[^\n\r]*%xmm3" 2 } } */
+/* { dg-prune-output "unsupported use of hardware register" } */
Index: gcc/testsuite/gcc.target/i386/avx512vl-abs-copysign-1.c
===================================================================
--- gcc/testsuite/gcc.target/i386/avx512vl-abs-copysign-1.c	(revision 266086)
+++ gcc/testsuite/gcc.target/i386/avx512vl-abs-copysign-1.c	(working copy)
@@ -69,3 +69,4 @@ f6 (double x)
 /* { dg-final { scan-assembler "vpandq\[^\n\r\]*xmm18" } } */
 /* { dg-final { scan-assembler "vporq\[^\n\r\]*xmm18" } } */
 /* { dg-final { scan-assembler "vpxorq\[^\n\r\]*xmm18" } } */
+/* { dg-prune-output "unsupported use of hardware register" } */
Index: gcc/testsuite/gcc.target/i386/avx512vl-abs-copysign-2.c
===================================================================
--- gcc/testsuite/gcc.target/i386/avx512vl-abs-copysign-2.c	(revision 266086)
+++ gcc/testsuite/gcc.target/i386/avx512vl-abs-copysign-2.c	(working copy)
@@ -47,3 +47,4 @@ f4 (void)
 /* { dg-final { scan-assembler "vpandq\[^\n\r\]*xmm16" } } */
 /* { dg-final { scan-assembler "vporq\[^\n\r\]*xmm16" } } */
 /* { dg-final { scan-assembler "vpxorq\[^\n\r\]*xmm16" } } */
+/* { dg-prune-output "unsupported use of hardware register" } */
Index: gcc/testsuite/gcc.target/i386/avx512vl-concatv2si-1.c
===================================================================
--- gcc/testsuite/gcc.target/i386/avx512vl-concatv2si-1.c	(revision 266086)
+++ gcc/testsuite/gcc.target/i386/avx512vl-concatv2si-1.c	(working copy)
@@ -41,3 +41,4 @@ f3 (int x, int *y)
 }
 
 /* { dg-final { scan-assembler-not "vpinsrd\[^\n\r]*\\\$1\[^\n\r]*%xmm16\[^\n\r]*%xmm3" } } */
+/* { dg-prune-output "unsupported use of hardware register" } */