combine.c (simplify_rtx): Obey CLASS_CANNOT_CHANGE_SIZE when simplifying a subreg...

        * combine.c (simplify_rtx): Obey CLASS_CANNOT_CHANGE_SIZE when
        simplifying a subreg of a hard reg.
        (expand_compound_operation): Likewise.
        (force_to_mode): Likewise.

From-SVN: r18052

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3733a2ad7202b8b2f4e43ae262a559743f9793ae..757b6aa018754412588c286836765dbc87490eea 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+Tue Feb 17 22:56:14 1998  Richard Henderson  <rth@cygnus.com>
+
+       * combine.c (simplify_rtx): Obey CLASS_CANNOT_CHANGE_SIZE when
+       simplifying a subreg of a hard reg.
+       (expand_compound_operation): Likewise.
+       (force_to_mode): Likewise.
+
 Tue Feb 17 22:37:22 1998  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
        * Makefile.in (gcc.o): Depend on system.h, in accordance with last

diff --git a/gcc/combine.c b/gcc/combine.c
index 81f4d9bb6e212a6b16d8a83743211c37fa733d27..dc8cc63853c38a210335a76ab1448f20bb516b54 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -3483,6 +3483,13 @@ simplify_rtx (x, op0_mode, last, in_dest)
 
       if (GET_CODE (SUBREG_REG (x)) == REG
          && REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
+#ifdef CLASS_CANNOT_CHANGE_SIZE
+         && (! (TEST_HARD_REG_BIT
+                (reg_class_contents[(int) CLASS_CANNOT_CHANGE_SIZE],
+                 REGNO (SUBREG_REG (x))))
+             || (GET_MODE_SIZE (mode)
+                 == GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
+#endif
          && REGNO (SUBREG_REG (x)) != FRAME_POINTER_REGNUM
 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
          && REGNO (SUBREG_REG (x)) != HARD_FRAME_POINTER_REGNUM
@@ -5106,6 +5113,20 @@ expand_compound_operation (x)
   int modewidth;
   rtx tem;
 
+#ifdef CLASS_CANNOT_CHANGE_SIZE
+  /* When dealing with hard regs that cannot change size, don't even try
+     expanding to shifts, since we wind up violating the rule.  */
+  if (GET_RTX_CLASS (GET_CODE (x)) == '1'
+      && GET_CODE (XEXP (x, 0)) == REG
+      && REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
+      && (TEST_HARD_REG_BIT
+         (reg_class_contents[(int) CLASS_CANNOT_CHANGE_SIZE],
+          REGNO (SUBREG_REG (x))))
+      && (GET_MODE_SIZE (GET_MODE (x))
+         != GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
+    return x;
+#endif
+
   switch (GET_CODE (x))
     {
     case ZERO_EXTEND:
@@ -6222,6 +6243,17 @@ force_to_mode (x, mode, mask, reg, just_select)
       break;
 
     case SUBREG:
+#ifdef CLASS_CANNOT_CHANGE_SIZE
+      if (GET_CODE (SUBREG_REG (x)) == REG
+         && REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
+         && (TEST_HARD_REG_BIT
+             (reg_class_contents[(int) CLASS_CANNOT_CHANGE_SIZE],
+              REGNO (SUBREG_REG (x))))
+         && (GET_MODE_SIZE (GET_MODE (x))
+             != GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
+       return x;
+#endif
+
       if (subreg_lowpart_p (x)
          /* We can ignore the effect of this SUBREG if it narrows the mode or
             if the constant masks to zero all the bits the mode doesn't