Commit Graph

11 Commits

Author SHA1 Message Date
Haicheng Wu 6d14dfe8f3 [InlineCost] Find more free binary operations
Currently, inline cost model considers a binary operator as free only if both
its operands are constants. Some simple cases are missing such as a + 0, a - a,
etc. This patch modifies visitBinaryOperator() to call SimplifyBinOp() without
going through simplifyInstruction() to get rid of the constant restriction.
Thus, visitAnd() and visitOr() are not needed.

Differential Revision: https://reviews.llvm.org/D41494

llvm-svn: 321366
2017-12-22 17:09:09 +00:00
Haicheng Wu 3739e14ab4 [InlineCost] Tracking Values through PHI Nodes
This patch fix this FIXME in visitPHI()

FIXME: We should potentially be tracking values through phi nodes,
especially when they collapse to a single value due to deleted CFG edges
during inlining.

Differential Revision: https://reviews.llvm.org/D38594

llvm-svn: 320699
2017-12-14 14:36:18 +00:00
Haicheng Wu 3ec848bc50 [InlineCost] add visitSelectInst()
InlineCost can understand Select IR now.  This patch finds free Select IRs and
continue the propagation of SimplifiedValues, ConstantOffsetPtrs, and
SROAArgValues.

Differential Revision: https://reviews.llvm.org/D37198

llvm-svn: 314307
2017-09-27 14:44:56 +00:00
Chad Rosier 2e1c050e52 [InlineCost] Simplify more 'and' and 'or' operations.
Differential Revision: https://reviews.llvm.org/D35856

llvm-svn: 309817
2017-08-02 14:40:42 +00:00
Haicheng Wu abdef9ee7e [TTI] Refine the cost of EXT in getUserCost()
Now, getUserCost() only checks the src and dst types of EXT to decide it is free
or not. This change first checks the types, then calls isExtFreeImpl(), and
check if EXT can form ExtLoad at last. Currently, only AArch64 has customized
implementation of isExtFreeImpl() to check if EXT can be folded into its use.

Differential Revision: https://reviews.llvm.org/D34458

llvm-svn: 308076
2017-07-15 02:12:16 +00:00
Florian Hahn 2665febb54 [AArch64] Inline callee if its target-features are a subset of the caller
Summary:
Similar to X86, it should be safe to inline callees if their target-features
are a subset of the caller. This change matches GCC's inlining behavior
with respect to attributes [1].

[1] https://gcc.gnu.org/onlinedocs/gcc/AArch64-Function-Attributes.html#AArch64-Function-Attributes

Reviewers: kristof.beyls, javed.absar, rengolin, t.p.northover

Reviewed By: t.p.northover

Subscribers: aemerson, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D34698

llvm-svn: 306478
2017-06-27 22:27:32 +00:00
Jun Bum Lim 506cfb7ab7 [InlineCost] Do not take INT_MAX when Cost is negative
Summary: visitSwitchInst should not take INT_MAX when Cost is negative. Instead of INT_MAX , we also use a valid upperbound cost when overflow occurs in Cost.

Reviewers: hans, echristo, dmgreen

Reviewed By: dmgreen

Subscribers: mcrosier, javed.absar, llvm-commits, eraman

Differential Revision: https://reviews.llvm.org/D34436

llvm-svn: 306118
2017-06-23 16:12:37 +00:00
Jun Bum Lim 2960d41e68 [InlineCost] Enable the new switch cost heuristic
Summary:
This is to enable the new switch inline cost heuristic (r301649) by removing the
old heuristic as well as the flag itself.
In my experiment for LLVM test suite and spec2000/2006, +17.82% performance and
8% code size reduce was observed in spec2000/vertex with O3 LTO in AArch64.
No significant code size / performance regression was found in O3/O2/Os. No
significant complain was reported from the llvm-dev thread.

Reviewers: hans, chandlerc, eraman, haicheng, mcrosier, bmakam, eastig, ddibyend, echristo

Reviewed By: echristo

Subscribers: javed.absar, kristof.beyls, echristo, aemerson, rengolin, mehdi_amini

Differential Revision: https://reviews.llvm.org/D32653

llvm-svn: 304594
2017-06-02 20:42:54 +00:00
Haicheng Wu bf277f38ad [InlineCost] Add a test case for GEP cost
The added test case is to check whether the simplified value is passed to
getGEPCost().

Differential Revision: https://reviews.llvm.org/D33779

llvm-svn: 304454
2017-06-01 19:06:07 +00:00
Jun Bum Lim 919f9e8d65 [InlineCost] Improve the cost heuristic for Switch
Summary:
The motivation example is like below which has 13 cases but only 2 distinct targets

```
lor.lhs.false2:                                   ; preds = %if.then
  switch i32 %Status, label %if.then27 [
    i32 -7012, label %if.end35
    i32 -10008, label %if.end35
    i32 -10016, label %if.end35
    i32 15000, label %if.end35
    i32 14013, label %if.end35
    i32 10114, label %if.end35
    i32 10107, label %if.end35
    i32 10105, label %if.end35
    i32 10013, label %if.end35
    i32 10011, label %if.end35
    i32 7008, label %if.end35
    i32 7007, label %if.end35
    i32 5002, label %if.end35
  ]
```
which is compiled into a balanced binary tree like this on AArch64 (similar on X86)

```
.LBB853_9:                              // %lor.lhs.false2
        mov     w8, #10012
        cmp             w19, w8
        b.gt    .LBB853_14
// BB#10:                               // %lor.lhs.false2
        mov     w8, #5001
        cmp             w19, w8
        b.gt    .LBB853_18
// BB#11:                               // %lor.lhs.false2
        mov     w8, #-10016
        cmp             w19, w8
        b.eq    .LBB853_23
// BB#12:                               // %lor.lhs.false2
        mov     w8, #-10008
        cmp             w19, w8
        b.eq    .LBB853_23
// BB#13:                               // %lor.lhs.false2
        mov     w8, #-7012
        cmp             w19, w8
        b.eq    .LBB853_23
        b       .LBB853_3
.LBB853_14:                             // %lor.lhs.false2
        mov     w8, #14012
        cmp             w19, w8
        b.gt    .LBB853_21
// BB#15:                               // %lor.lhs.false2
        mov     w8, #-10105
        add             w8, w19, w8
        cmp             w8, #9          // =9
        b.hi    .LBB853_17
// BB#16:                               // %lor.lhs.false2
        orr     w9, wzr, #0x1
        lsl     w8, w9, w8
        mov     w9, #517
        and             w8, w8, w9
        cbnz    w8, .LBB853_23
.LBB853_17:                             // %lor.lhs.false2
        mov     w8, #10013
        cmp             w19, w8
        b.eq    .LBB853_23
        b       .LBB853_3
.LBB853_18:                             // %lor.lhs.false2
        mov     w8, #-7007
        add             w8, w19, w8
        cmp             w8, #2          // =2
        b.lo    .LBB853_23
// BB#19:                               // %lor.lhs.false2
        mov     w8, #5002
        cmp             w19, w8
        b.eq    .LBB853_23
// BB#20:                               // %lor.lhs.false2
        mov     w8, #10011
        cmp             w19, w8
        b.eq    .LBB853_23
        b       .LBB853_3
.LBB853_21:                             // %lor.lhs.false2
        mov     w8, #14013
        cmp             w19, w8
        b.eq    .LBB853_23
// BB#22:                               // %lor.lhs.false2
        mov     w8, #15000
        cmp             w19, w8
        b.ne    .LBB853_3
```
However, the inline cost model estimates the cost to be linear with the number
of distinct targets and the cost of the above switch is just 2 InstrCosts.
The function containing this switch is then inlined about 900 times.

This change use the general way of switch lowering for the inline heuristic. It
etimate the number of case clusters with the suitability check for a jump table
or bit test. Considering the binary search tree built for the clusters, this
change modifies the model to be linear with the size of the balanced binary
tree. The model is off by default for now :
  -inline-generic-switch-cost=false

This change was originally proposed by Haicheng in D29870.

Reviewers: hans, bmakam, chandlerc, eraman, haicheng, mcrosier

Reviewed By: hans

Subscribers: joerg, aemerson, llvm-commits, rengolin

Differential Revision: https://reviews.llvm.org/D31085

llvm-svn: 301649
2017-04-28 16:04:03 +00:00
Haicheng Wu 201b191b82 Recommit "[InlineCost] Use TTI to check if GEP is free." #3
This is the third attemp to recommit r292526.

The original summary:

Currently, a GEP is considered free only if its indices are all constant.
TTI::getGEPCost() can give target-specific more accurate analysis. TTI is
already used for the cost of many other instructions.

llvm-svn: 292633
2017-01-20 18:51:22 +00:00