From 9134df2c6c398e67f0cb5e008a6b84b7fbb029e6 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Mon, 6 Nov 2017 14:47:43 +0000 Subject: [PATCH] PR82816: Widening multiplies of bitfields In this PR we tried to create a widening multiply of two 3-bit numbers, but that isn't a widening multiply at the optab/rtl level, since both the input and output still have the same mode. We could trap this either in is_widening_mult_p or (as the patch does) in the routines that actually ask for an optab. The latter seemed more natural since is_widening_mult_p doesn't otherwise care about modes. 2017-11-03 Richard Sandiford Alan Hayward David Sherwood gcc/ PR tree-optimization/82816 * tree-ssa-math-opts.c (convert_mult_to_widen): Return false if the modes of the two types are the same. (convert_plusminus_to_widen): Likewise. gcc/testsuite/ * gcc.c-torture/compile/pr82816.c: New test. Co-Authored-By: Alan Hayward Co-Authored-By: David Sherwood From-SVN: r254454 --- gcc/ChangeLog | 9 +++++++++ gcc/testsuite/ChangeLog | 6 ++++++ gcc/testsuite/gcc.c-torture/compile/pr82816.c | 12 ++++++++++++ gcc/tree-ssa-math-opts.c | 6 ++++++ 4 files changed, 33 insertions(+) create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr82816.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 6ba0a80..4ff37f4 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,12 @@ +2017-11-06 Richard Sandiford + Alan Hayward + David Sherwood + + PR tree-optimization/82816 + * tree-ssa-math-opts.c (convert_mult_to_widen): Return false + if the modes of the two types are the same. + (convert_plusminus_to_widen): Likewise. + 2017-11-06 Bill Schmidt * config/rs6000/altivec.md (*p9_vadu3) Rename to diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index dde8a35..d098cfc 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2017-11-06 Richard Sandiford + Alan Hayward + David Sherwood + + * gcc.c-torture/compile/pr82816.c: New test. + 2017-11-06 Bill Schmidt * gcc.target/powerpc/sad-vectorize-1.c: New file. diff --git a/gcc/testsuite/gcc.c-torture/compile/pr82816.c b/gcc/testsuite/gcc.c-torture/compile/pr82816.c new file mode 100644 index 0000000..8e9bd00 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/compile/pr82816.c @@ -0,0 +1,12 @@ +struct A +{ + int b:3; +} d, e; + +int c; + +void f () +{ + char g = d.b * e.b; + c = g; +} diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c index 493f4e2..5986ac1 100644 --- a/gcc/tree-ssa-math-opts.c +++ b/gcc/tree-ssa-math-opts.c @@ -3259,6 +3259,9 @@ convert_mult_to_widen (gimple *stmt, gimple_stmt_iterator *gsi) to_mode = SCALAR_INT_TYPE_MODE (type); from_mode = SCALAR_INT_TYPE_MODE (type1); + if (to_mode == from_mode) + return false; + from_unsigned1 = TYPE_UNSIGNED (type1); from_unsigned2 = TYPE_UNSIGNED (type2); @@ -3449,6 +3452,9 @@ convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple *stmt, to_mode = SCALAR_TYPE_MODE (type); from_mode = SCALAR_TYPE_MODE (type1); + if (to_mode == from_mode) + return false; + from_unsigned1 = TYPE_UNSIGNED (type1); from_unsigned2 = TYPE_UNSIGNED (type2); optype = type1; -- 2.7.4