diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6de127a3dcc..002d84494d4 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2001-04-20  Jakub Jelinek  <jakub@redhat.com>
+
+	* reg-stack.c (check_asm_stack_operands): Issue error if "=t" resp.
+	"=u" is used together with "st" resp. "st(1)" clobber.
+
 2001-04-20  Jakub Jelinek  <jakub@redhat.com>
 
 	* gcse.c (gcse_main): Fix comment typo.
diff --git a/gcc/reg-stack.c b/gcc/reg-stack.c
index 43bedebd90a..6327b24e96e 100644
--- a/gcc/reg-stack.c
+++ b/gcc/reg-stack.c
@@ -662,7 +662,20 @@ check_asm_stack_operands (insn)
 	    malformed_asm = 1;
 	  }
         else
-	  reg_used_as_output[REGNO (recog_data.operand[i])] = 1;
+	  {
+	    int j;
+
+	    for (j = 0; j < n_clobbers; j++)
+	      if (REGNO (recog_data.operand[i]) == REGNO (clobber_reg[j]))
+		{
+		  error_for_asm (insn, "Output constraint %d cannot be specified together with \"%s\" clobber",
+				 i, reg_names [REGNO (clobber_reg[j])]);
+		  malformed_asm = 1;
+		  break;
+		}
+	    if (j == n_clobbers)
+	      reg_used_as_output[REGNO (recog_data.operand[i])] = 1;
+	  }
       }