From patchwork Wed Jun 27 22:16:12 2012
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Subject: Add MULT_HIGHPART_EXPR
Date: Wed, 27 Jun 2012 12:16:12 -0000
From: Richard Henderson <rth@redhat.com>
X-Patchwork-Id: 167754
Message-Id: <4FEB862C.2050904@redhat.com>
To: Steven Bosscher <stevenb.gcc@gmail.com>
Cc: gcc-patches@gcc.gnu.org

On 06/27/2012 02:42 PM, Steven Bosscher wrote:
> Maybe also a bit in doc/generic.texi? Or is this not supposed to be
> exposed to the front ends?

I can't imagine it being terribly useful to front ends, but there's
certainly nothing that ought to prevent it.  How's this?


r~


diff --git a/gcc/doc/generic.texi b/gcc/doc/generic.texi
index e99366f..c48b663 100644
--- a/gcc/doc/generic.texi
+++ b/gcc/doc/generic.texi
@@ -1235,6 +1235,7 @@ the byte offset of the field, but should not be used directly; call
 @tindex PLUS_EXPR
 @tindex MINUS_EXPR
 @tindex MULT_EXPR
+@tindex MULT_HIGHPART_EXPR
 @tindex RDIV_EXPR
 @tindex TRUNC_DIV_EXPR
 @tindex FLOOR_DIV_EXPR
@@ -1433,6 +1434,11 @@ one operand is of floating type and the other is of integral type.
 The behavior of these operations on signed arithmetic overflow is
 controlled by the @code{flag_wrapv} and @code{flag_trapv} variables.
 
+@item MULT_HIGHPART_EXPR
+This node represents the ``high-part'' of a widening multiplication.
+For an integral type with @var{b} bits of precision, the result is
+the most significant @var{b} bits of the full @math{2@var{b}} product.
+
 @item RDIV_EXPR
 This node represents a floating point division operation.