From 535251487ba56c4fd98465c4682881c2b9734242 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Fri, 15 Feb 2019 14:52:20 -0800 Subject: [PATCH] nir: Don't reassociate add/mul chains containing only constants The idea here is to reassociate a * (b * c) into (a * c) * b, when b is a non-constant value, but a and c are constants, allowing them to be combined. But nothing was enforcing that 'b' must be non-constant, which meant that running opt_algebraic in a loop would never terminate if the IR contained non-folded constant expressions like 256 * 0.5 * 2. Normally, we call constant folding in such a loop too, but IMO it's better for nir_opt_algebraic to be robust and not rely on that. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109581 Fixes: 32e266a9a58 i965: Compile fp64 funcs only if we do not have 64-bit hardware support Reviewed-by: Ian Romanick --- src/compiler/nir/nir_opt_algebraic.py | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py index 073e799..ba27d70 100644 --- a/src/compiler/nir/nir_opt_algebraic.py +++ b/src/compiler/nir/nir_opt_algebraic.py @@ -636,11 +636,11 @@ optimizations = [ # Reassociate constants in add/mul chains so they can be folded together. # For now, we mostly only handle cases where the constants are separated by # a single non-constant. We could do better eventually. - (('~fmul', '#a', ('fmul', b, '#c')), ('fmul', ('fmul', a, c), b)), - (('imul', '#a', ('imul', b, '#c')), ('imul', ('imul', a, c), b)), - (('~fadd', '#a', ('fadd', b, '#c')), ('fadd', ('fadd', a, c), b)), - (('~fadd', '#a', ('fneg', ('fadd', b, '#c'))), ('fadd', ('fadd', a, ('fneg', c)), ('fneg', b))), - (('iadd', '#a', ('iadd', b, '#c')), ('iadd', ('iadd', a, c), b)), + (('~fmul', '#a', ('fmul', 'b(is_not_const)', '#c')), ('fmul', ('fmul', a, c), b)), + (('imul', '#a', ('imul', 'b(is_not_const)', '#c')), ('imul', ('imul', a, c), b)), + (('~fadd', '#a', ('fadd', 'b(is_not_const)', '#c')), ('fadd', ('fadd', a, c), b)), + (('~fadd', '#a', ('fneg', ('fadd', 'b(is_not_const)', '#c'))), ('fadd', ('fadd', a, ('fneg', c)), ('fneg', b))), + (('iadd', '#a', ('iadd', 'b(is_not_const)', '#c')), ('iadd', ('iadd', a, c), b)), # By definition... (('bcsel', ('ige', ('find_lsb', a), 0), ('find_lsb', a), -1), ('find_lsb', a)), -- 2.7.4