When doing the initial pass of constant folding, if we get a constantexpr,
simplify the constant expr like we would do if the constant is folded in the
normal loop.
This fixes the missed-optimization regression in
Transforms/InstCombine/getelementptr.ll last night.
llvm-svn: 28224
1. Implement InstCombine/deadcode.ll by not adding instructions in unreachable
blocks (due to constants in conditional branches/switches) to the worklist.
This causes them to be deleted before instcombine starts up, leading to
better optimization.
2. In the prepass over instructions, do trivial constprop/dce as we go. This
has the effect of improving the effectiveness of #1. In addition, it
*significantly* speeds up instcombine on test cases with large amounts of
constant folding code (for example, that produced by code specialization
or partial evaluation). In one example, it speeds up instcombine from
0.0589s to 0.0224s with a release build (a 2.6x speedup).
llvm-svn: 28215
Make the "fold (and (cast A), (cast B)) -> (cast (and A, B))" transformation
only apply when both casts really will cause code to be generated. If one or
both doesn't, then this xform doesn't remove a cast.
This fixes Transforms/InstCombine/2006-05-06-Infloop.ll
llvm-svn: 28141
%tmp = cast <4 x uint> %tmp to <4 x int> ; <<4 x int>> [#uses=1]
%tmp = cast <4 x int> %tmp to <4 x float> ; <<4 x float>> [#uses=1]
into:
%tmp = cast <4 x uint> %tmp to <4 x float> ; <<4 x float>> [#uses=1]
llvm-svn: 27355
%tmp = cast <4 x uint>* %testData to <4 x int>* ; <<4 x int>*> [#uses=1]
%tmp = load <4 x int>* %tmp ; <<4 x int>> [#uses=1]
to this:
%tmp = load <4 x uint>* %testData ; <<4 x uint>> [#uses=1]
%tmp = cast <4 x uint> %tmp to <4 x int> ; <<4 x int>> [#uses=1]
llvm-svn: 27353
the pointer is known to come from either a global variable, alloca or
malloc. This allows us to compile this:
P = malloc(28);
memset(P, 0, 28);
into explicit stores on PPC instead of a memset call.
llvm-svn: 26577
Make this code more powerful by using ComputeMaskedBits instead of looking
for an AND operand. This lets us fold this:
int %test23(int %a) {
%tmp.1 = and int %a, 1
%tmp.2 = seteq int %tmp.1, 0
%tmp.3 = cast bool %tmp.2 to int ;; xor tmp1, 1
ret int %tmp.3
}
into: xor (and a, 1), 1
llvm-svn: 26396
1. Teach GetConstantInType to handle boolean constants.
2. Teach instcombine to fold (compare X, CST) when X has known 0/1 bits.
Testcase here: set.ll:test22
3. Improve the "(X >> c1) & C2 == 0" folding code to allow a noop cast
between the shift and and. More aggressive bitfolding for other reasons
was turning signed shr's into unsigned shr's, leaving the noop cast in
the way.
llvm-svn: 26131
This allows us to simplify on conditions where bits are not known, but they
are not demanded either! This also fixes a couple of bugs in
ComputeMaskedBits that were exposed during this work.
In the future, swaths of instcombine should be removed, as this code
subsumes a bunch of ad-hockery.
llvm-svn: 26122
1. Teach it new tricks: in particular how to propagate through signed shr and sexts.
2. Teach it to return a bitset of known-1 and known-0 bits, instead of just zero.
3. Teach instcombine (AND X, C) to fold when we know all C bits of X.
This implements Regression/Transforms/InstCombine/bittest.ll, and allows
future things to be simplified.
llvm-svn: 26087
instruction onto the worklist (in case they are now dead).
Add a really trivial local DSE implementation to help out bitfield code.
We now fold this:
struct S {
unsigned char a : 1, b : 1, c : 1, d : 2, e : 3;
S();
};
S::S() : a(0), b(0), c(1), d(0), e(6) {}
to this:
void %_ZN1SC1Ev(%struct.S* %this) {
entry:
%tmp.1 = getelementptr %struct.S* %this, int 0, uint 0
store ubyte 38, ubyte* %tmp.1
ret void
}
much earlier (in gccas instead of only in gccld after DSE runs).
llvm-svn: 26050
mask. This allows the code to be simpler and more efficient.
Also, generalize some of the cases in MVIZ a bit, making it slightly more aggressive.
llvm-svn: 26035
'demanded bits', inspired by Nate's work in the dag combiner. This isn't
complete, but needs to unrelated instcombiner changes to continue.
llvm-svn: 26033
the shifts.
This allows us to fold this (which is the 'integer add a constant' sequence
from cozmic's scheme compmiler):
int %x(uint %anf-temporary776) {
%anf-temporary777 = shr uint %anf-temporary776, ubyte 1
%anf-temporary800 = cast uint %anf-temporary777 to int
%anf-temporary804 = shl int %anf-temporary800, ubyte 1
%anf-temporary805 = add int %anf-temporary804, -2
%anf-temporary806 = or int %anf-temporary805, 1
ret int %anf-temporary806
}
into this:
int %x(uint %anf-temporary776) {
%anf-temporary776 = cast uint %anf-temporary776 to int
%anf-temporary776.mask1 = add int %anf-temporary776, -2
%anf-temporary805 = or int %anf-temporary776.mask1, 1
ret int %anf-temporary805
}
note that instcombine already knew how to eliminate the AND that the two
shifts fold into. This is tested by InstCombine/shift.ll:test26
-Chris
llvm-svn: 25128
Add support for specifying alignment and size of setjmp jmpbufs.
No targets currently do anything with this information, nor is it presrved
in the bytecode representation. That's coming up next.
llvm-svn: 24196
a few times in crafty:
OLD: %tmp.36 = div int %tmp.35, 8 ; <int> [#uses=1]
NEW: %tmp.36 = div uint %tmp.35, 8 ; <uint> [#uses=0]
OLD: %tmp.19 = div int %tmp.18, 8 ; <int> [#uses=1]
NEW: %tmp.19 = div uint %tmp.18, 8 ; <uint> [#uses=0]
OLD: %tmp.117 = div int %tmp.116, 8 ; <int> [#uses=1]
NEW: %tmp.117 = div uint %tmp.116, 8 ; <uint> [#uses=0]
OLD: %tmp.92 = div int %tmp.91, 8 ; <int> [#uses=1]
NEW: %tmp.92 = div uint %tmp.91, 8 ; <uint> [#uses=0]
Which all turn into shrs.
llvm-svn: 24190
8 times in vortex, allowing the srems to be turned into shrs:
OLD: %tmp.104 = rem int %tmp.5.i37, 16 ; <int> [#uses=1]
NEW: %tmp.104 = rem uint %tmp.5.i37, 16 ; <uint> [#uses=0]
OLD: %tmp.98 = rem int %tmp.5.i24, 16 ; <int> [#uses=1]
NEW: %tmp.98 = rem uint %tmp.5.i24, 16 ; <uint> [#uses=0]
OLD: %tmp.91 = rem int %tmp.5.i19, 8 ; <int> [#uses=1]
NEW: %tmp.91 = rem uint %tmp.5.i19, 8 ; <uint> [#uses=0]
OLD: %tmp.88 = rem int %tmp.5.i14, 8 ; <int> [#uses=1]
NEW: %tmp.88 = rem uint %tmp.5.i14, 8 ; <uint> [#uses=0]
OLD: %tmp.85 = rem int %tmp.5.i9, 1024 ; <int> [#uses=2]
NEW: %tmp.85 = rem uint %tmp.5.i9, 1024 ; <uint> [#uses=0]
OLD: %tmp.82 = rem int %tmp.5.i, 512 ; <int> [#uses=2]
NEW: %tmp.82 = rem uint %tmp.5.i1, 512 ; <uint> [#uses=0]
OLD: %tmp.48.i = rem int %tmp.5.i.i161, 4 ; <int> [#uses=1]
NEW: %tmp.48.i = rem uint %tmp.5.i.i161, 4 ; <uint> [#uses=0]
OLD: %tmp.20.i2 = rem int %tmp.5.i.i, 4 ; <int> [#uses=1]
NEW: %tmp.20.i2 = rem uint %tmp.5.i.i, 4 ; <uint> [#uses=0]
it also occurs 9 times in gcc, but with odd constant divisors (1009 and 61)
so the payoff isn't as great.
llvm-svn: 24189
one use (but one is a cast). This handles the very common case of:
X = alloc [n x byte]
Y = cast X to somethingbetter
seteq X, null
In order to avoid infinite looping when there are multiple casts, we only
allow this if the xform is strictly increasing the alignment of the
allocation.
llvm-svn: 23961
where the second has less alignment required. If we had explicit alignment
support in the IR, we could handle this case, but we can't until we do.
llvm-svn: 23960
Chris Lattner