ubsan: bfin: shift exponent is too large

This was the following in fmtconst_val, x is unsigned int.
    x = SIGNEXTEND (x, constant_formats[cf].nbits);
Problem is, the SIGNEXTEND macro assumed its arg was a long and sign
extended by shifting left then shifting right, and didn't cast the
arg.  So don't do the silly shift thing.  It's not guaranteed to work
anyway according to the C standard.  ">>" might do a logical shift
even if its args are signed.

	* bfin-dis.c (HOST_LONG_WORD_SIZE, XFIELD): Delete.
	(SIGNBIT): New.
	(MASKBITS, SIGNEXTEND): Rewrite.
	(fmtconst): Don't use ? expression now that SIGNEXTEND uses
	unsigned arithmetic, instead assign result of SIGNEXTEND back
	to x.
	(fmtconst_val): Use 1u in shift expression.

2 files changed, 26 insertions, 13 deletions

diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index d3f1e69..faa160a 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,5 +1,15 @@
 2019-12-11  Alan Modra  <amodra@gmail.com>
 
+	* bfin-dis.c (HOST_LONG_WORD_SIZE, XFIELD): Delete.
+	(SIGNBIT): New.
+	(MASKBITS, SIGNEXTEND): Rewrite.
+	(fmtconst): Don't use ? expression now that SIGNEXTEND uses
+	unsigned arithmetic, instead assign result of SIGNEXTEND back
+	to x.
+	(fmtconst_val): Use 1u in shift expression.
+
+2019-12-11  Alan Modra  <amodra@gmail.com>
+
 	* arc-dis.c (find_format_from_table): Use ull constant when
 	shifting by up to 32.
 
diff --git a/opcodes/bfin-dis.c b/opcodes/bfin-dis.c
index 811509f..711f7e1 100644
--- a/opcodes/bfin-dis.c
+++ b/opcodes/bfin-dis.c
@@ -33,10 +33,9 @@
 
 typedef long TIword;
 
-#define HOST_LONG_WORD_SIZE (sizeof (long) * 8)
-#define XFIELD(w,p,s)       (((w) & ((1 << (s)) - 1) << (p)) >> (p))
-#define SIGNEXTEND(v, n)    ((v << (HOST_LONG_WORD_SIZE - (n))) >> (HOST_LONG_WORD_SIZE - (n)))
-#define MASKBITS(val, bits) (val & ((1 << bits) - 1))
+#define SIGNBIT(bits)       (1ul << ((bits) - 1))
+#define MASKBITS(val, bits) ((val) & ((1ul << (bits)) - 1))
+#define SIGNEXTEND(v, n)    ((MASKBITS (v, n) ^ SIGNBIT (n)) - SIGNBIT (n))
 
 #include "disassemble.h"
 
@@ -125,8 +124,11 @@ fmtconst (const_forms_t cf, TIword x, bfd_vma pc, disassemble_info *outf)
 
   if (constant_formats[cf].reloc)
     {
-      bfd_vma ea = (((constant_formats[cf].pcrel ? SIGNEXTEND (x, constant_formats[cf].nbits)
-		      : x) + constant_formats[cf].offset) << constant_formats[cf].scale);
+      bfd_vma ea;
+
+      if (constant_formats[cf].pcrel)
+	x = SIGNEXTEND (x, constant_formats[cf].nbits);
+      ea = (x + constant_formats[cf].offset) << constant_formats[cf].scale;
       if (constant_formats[cf].pcrel)
 	ea += pc;
 
@@ -153,8 +155,8 @@ fmtconst (const_forms_t cf, TIword x, bfd_vma pc, disassemble_info *outf)
       x = x | (1 << constant_formats[cf].nbits);
       x = SIGNEXTEND (x, nb);
     }
-  else
-    x = constant_formats[cf].issigned ? SIGNEXTEND (x, constant_formats[cf].nbits) : x;
+  else if (constant_formats[cf].issigned)
+    x = SIGNEXTEND (x, constant_formats[cf].nbits);
 
   if (constant_formats[cf].offset)
     x += constant_formats[cf].offset;
@@ -180,10 +182,11 @@ fmtconst_val (const_forms_t cf, unsigned int x, unsigned int pc)
 {
   if (0 && constant_formats[cf].reloc)
     {
-      bu32 ea = (((constant_formats[cf].pcrel
-		   ? SIGNEXTEND (x, constant_formats[cf].nbits)
-		   : x) + constant_formats[cf].offset)
-		 << constant_formats[cf].scale);
+      bu32 ea;
+
+      if (constant_formats[cf].pcrel)
+	x = SIGNEXTEND (x, constant_formats[cf].nbits);
+      ea = (x + constant_formats[cf].offset) << constant_formats[cf].scale;
       if (constant_formats[cf].pcrel)
 	ea += pc;
 
@@ -194,7 +197,7 @@ fmtconst_val (const_forms_t cf, unsigned int x, unsigned int pc)
   if (constant_formats[cf].negative)
     {
       int nb = constant_formats[cf].nbits + 1;
-      x = x | (1 << constant_formats[cf].nbits);
+      x = x | (1u << constant_formats[cf].nbits);
       x = SIGNEXTEND (x, nb);
     }
   else if (constant_formats[cf].issigned)