From fc98d038618b792c413212759057b2125507d3ef Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Tue, 4 Feb 2020 10:03:03 +0100 Subject: [PATCH] tree-optimization/92819 restrict new vector CTOR canonicalization The PR shows that code generation ends up pessimized by the new canonicalization rules that end up nailing do-not-care elements to specific values making it hard to generate good code later. The temporary solution is to avoid this for the cases we also obviously know the canonicalization will create more GIMPLE stmts than before. 2020-02-04 Richard Biener PR tree-optimization/92819 * tree-ssa-forwprop.c (simplify_vector_constructor): Avoid generating more stmts than before. * gcc.target/i386/pr92819.c: New testcase. * gcc.target/i386/pr92803.c: Adjust. --- gcc/ChangeLog | 6 ++++ gcc/testsuite/ChangeLog | 6 ++++ gcc/testsuite/gcc.target/i386/pr92803.c | 5 +-- gcc/testsuite/gcc.target/i386/pr92819.c | 45 +++++++++++++++++++++++++ gcc/tree-ssa-forwprop.c | 15 +++++++-- 5 files changed, 73 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/pr92819.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 59d606b8645..4a5dddb4ecf 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2020-02-04 Richard Biener + + PR tree-optimization/92819 + * tree-ssa-forwprop.c (simplify_vector_constructor): Avoid + generating more stmts than before. + 2020-02-04 Martin Liska * config/arm/arm.c (arm_gen_far_branch): Move the function diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 28ecbe1472e..1624f592ae7 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2020-02-04 Richard Biener + + PR tree-optimization/92819 + * gcc.target/i386/pr92819.c: New testcase. + * gcc.target/i386/pr92803.c: Adjust. + 2020-02-03 Iain Sandoe PR c++/93458 diff --git a/gcc/testsuite/gcc.target/i386/pr92803.c b/gcc/testsuite/gcc.target/i386/pr92803.c index d533bae0c26..6d4c07a7480 100644 --- a/gcc/testsuite/gcc.target/i386/pr92803.c +++ b/gcc/testsuite/gcc.target/i386/pr92803.c @@ -36,5 +36,6 @@ barf (v8sf x) /* We expect all other CTORs to turn into permutes, the FP converting ones to two each with the one with constants possibly elided in the future by converting 3.0f and 1.0f "back" to integers. */ -/* { dg-final { scan-tree-dump-times "VEC_PERM_EXPR" 4 "forwprop1" } } */ -/* { dg-final { scan-tree-dump-times "VEC_PERM_EXPR" 3 "forwprop1" { xfail *-*-* } } } */ +/* For foo we do nothing. */ +/* { dg-final { scan-tree-dump-times "VEC_PERM_EXPR" 3 "forwprop1" } } */ +/* { dg-final { scan-tree-dump-times "VEC_PERM_EXPR" 2 "forwprop1" { xfail *-*-* } } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr92819.c b/gcc/testsuite/gcc.target/i386/pr92819.c new file mode 100644 index 00000000000..773e3490ab3 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr92819.c @@ -0,0 +1,45 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mavx2 -fdump-tree-forwprop1" } */ + +typedef double v4df __attribute__((vector_size (32))); +typedef double v2df __attribute__((vector_size (16))); +typedef short v16hi __attribute__((vector_size (32))); +typedef short v8hi __attribute__((vector_size (16))); + +v2df +foo (v4df x, double *p) +{ + return (v2df) { x[1], *p }; +} + +v2df +bar (v4df x, double *p) +{ + return (v2df) { x[0], *p }; /* BIT_INSERT_EXPR */ +} + +v2df +baz (v2df x, double *p) +{ + return (v2df) { x[1], *p }; /* VEC_PERM_EXPR */ +} + +v2df +qux (v2df x, double *p) +{ + return (v2df) { x[0], *p }; /* BIT_INSERT_EXPR */ +} + +v2df +corge (v4df x, double *p) +{ + return (v2df) { x[3], *p }; +} + +/* { dg-final { scan-tree-dump-times "BIT_INSERT_EXPR" 2 "forwprop1" } } */ +/* { dg-final { scan-tree-dump-times "VEC_PERM_EXPR" 1 "forwprop1" } } */ +/* We can't check for 1:1 assembler here so check for what we do not + want to see. */ +/* { dg-final { scan-assembler-not { "perm" } } } */ +/* { dg-final { scan-assembler-not { "insert" } } } */ +/* { dg-final { scan-assembler-not { "broadcast" } } } */ diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c index 5203891950a..f65216d23e9 100644 --- a/gcc/tree-ssa-forwprop.c +++ b/gcc/tree-ssa-forwprop.c @@ -2230,7 +2230,6 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi) unsigned HOST_WIDE_INT refnelts; enum tree_code conv_code; constructor_elt *elt; - bool maybe_ident; op = gimple_assign_rhs1 (stmt); type = TREE_TYPE (op); @@ -2245,7 +2244,8 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi) orig[0] = NULL; orig[1] = NULL; conv_code = ERROR_MARK; - maybe_ident = true; + bool maybe_ident = true; + bool maybe_blend[2] = { true, true }; tree one_constant = NULL_TREE; tree one_nonconstant = NULL_TREE; auto_vec constants; @@ -2290,6 +2290,8 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi) orig[j] = ref; if (elem != i || j != 0) maybe_ident = false; + if (elem != i) + maybe_blend[j] = false; elts.safe_push (std::make_pair (j, elem)); continue; } @@ -2439,6 +2441,15 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi) } else { + /* If we combine a vector with a non-vector avoid cases where + we'll obviously end up with more GIMPLE stmts which is when + we'll later not fold this to a single insert into the vector + and we had a single extract originally. See PR92819. */ + if (nelts == 2 + && refnelts > 2 + && orig[1] == error_mark_node + && !maybe_blend[0]) + return false; tree mask_type, perm_type, conv_src_type; perm_type = TREE_TYPE (orig[0]); conv_src_type = (nelts == refnelts -- 2.30.2