Merged current trunk to branch.

1 files changed, 22 insertions, 9 deletions

diff --git a/gcc/reg-stack.c b/gcc/reg-stack.c
index 3dab843..1d9ea03 100644
--- a/gcc/reg-stack.c
+++ b/gcc/reg-stack.c
@@ -1,5 +1,5 @@
 /* Register to Stack convert for GNU compiler.
-   Copyright (C) 1992-2020 Free Software Foundation, Inc.
+   Copyright (C) 1992-2021 Free Software Foundation, Inc.
 
    This file is part of GCC.
 
@@ -174,6 +174,7 @@
 #include "reload.h"
 #include "tree-pass.h"
 #include "rtl-iter.h"
+#include "function-abi.h"
 
 #ifdef STACK_REGS
 
@@ -1251,7 +1252,7 @@ swap_rtx_condition (rtx_insn *insn)
 {
   rtx pat = PATTERN (insn);
 
-  /* We're looking for a single set to cc0 or an HImode temporary.  */
+  /* We're looking for a single set to an HImode temporary.  */
 
   if (GET_CODE (pat) == SET
       && REG_P (SET_DEST (pat))
@@ -1298,7 +1299,7 @@ swap_rtx_condition (rtx_insn *insn)
 	  || ! dead_or_set_p (insn, dest))
 	return 0;
 
-      /* Now we are prepared to handle this as a normal cc0 setter.  */
+      /* Now we are prepared to handle this.  */
       insn = next_flags_user (insn);
       if (insn == NULL_RTX)
 	return 0;
@@ -1586,9 +1587,7 @@ subst_stack_regs_pat (rtx_insn *insn, stack_ptr regstack, rtx pat)
 	    break;
 
 	  case REG:
-	    /* This is a `tstM2' case.  */
-	    gcc_assert (*dest == cc0_rtx);
-	    src1 = src;
+	    gcc_unreachable ();
 
 	    /* Fall through.  */
 
@@ -1596,8 +1595,7 @@ subst_stack_regs_pat (rtx_insn *insn, stack_ptr regstack, rtx pat)
 	  case SQRT:
 	  case ABS:
 	  case NEG:
-	    /* These insns only operate on the top of the stack. DEST might
-	       be cc0_rtx if we're processing a tstM pattern. Also, it's
+	    /* These insns only operate on the top of the stack.  It's
 	       possible that the tstM case results in a REG_DEAD note on the
 	       source.  */
 
@@ -2371,6 +2369,18 @@ subst_asm_stack_regs (rtx_insn *insn, stack_ptr regstack)
 	    }
       }
 }
+
+/* Return true if a function call is allowed to alter some or all bits
+   of any stack reg.  */
+static bool
+callee_clobbers_any_stack_reg (const function_abi & callee_abi)
+{
+  for (unsigned regno = FIRST_STACK_REG; regno <= LAST_STACK_REG; regno++)
+    if (callee_abi.clobbers_at_least_part_of_reg_p (regno))
+      return true;
+  return false;
+}
+
 
 /* Substitute stack hard reg numbers for stack virtual registers in
    INSN.  Non-stack register numbers are not changed.  REGSTACK is the
@@ -2385,7 +2395,10 @@ subst_stack_regs (rtx_insn *insn, stack_ptr regstack)
   bool control_flow_insn_deleted = false;
   int i;
 
-  if (CALL_P (insn))
+  /* If the target of the call doesn't clobber any stack registers,
+     Don't clear the arguments.  */
+  if (CALL_P (insn)
+      && callee_clobbers_any_stack_reg (insn_callee_abi (insn)))
     {
       int top = regstack->top;