RPCSX/llvm
1
0
Fork 0
mirror of https://github.com/RPCSX/llvm.git synced 2025-04-18 08:00:02 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

The patch turns on epilogue unroll for loops with constant recurency start.

Browse Source 
Summary:

Set unroll remainder to epilog if a loop contains a phi with constant parameter:

  loop:
  pn = phi [Const, PreHeader], [pn.next, Latch]
  ...

Reviewer: hfinkel

Differential Revision: http://reviews.llvm.org/D27004

From: Evgeny Stupachenko <evstupac@gmail.com>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296770 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evgeny Stupachenko 2017-03-02 17:38:46 +00:00
parent d541a8113c
commit c40a2f9b2a
5 changed files with 65 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
lib/Transforms/Utils/LoopUnroll.cpp
View File

@ -216,6 +216,45 @@ const Loop* llvm::addClonedBlockToLoopInfo(BasicBlock *OriginalBB,
}
}
/// The function chooses which type of unroll (epilog or prolog) is more
/// profitabale.
/// Epilog unroll is more profitable when there is PHI that starts from
/// constant. In this case epilog will leave PHI start from constant,
/// but prolog will convert it to non-constant.
///
/// loop:
/// PN = PHI [I, Latch], [CI, PreHeader]
/// I = foo(PN)
/// ...
///
/// Epilog unroll case.
/// loop:
/// PN = PHI [I2, Latch], [CI, PreHeader]
/// I1 = foo(PN)
/// I2 = foo(I1)
/// ...
/// Prolog unroll case.
/// NewPN = PHI [PrologI, Prolog], [CI, PreHeader]
/// loop:
/// PN = PHI [I2, Latch], [NewPN, PreHeader]
/// I1 = foo(PN)
/// I2 = foo(I1)
/// ...
///
static bool isEpilogProfitable(Loop *L) {
BasicBlock *PreHeader = L->getLoopPreheader();
BasicBlock *Header = L->getHeader();
assert(PreHeader && Header);
for (Instruction &BBI : *Header) {
PHINode *PN = dyn_cast<PHINode>(&BBI);
if (!PN)
break;
if (isa<ConstantInt>(PN->getIncomingValueForBlock(PreHeader)))
return true;
}
return false;
}
/// Unroll the given loop by Count. The loop must be in LCSSA form. Returns true
/// if unrolling was successful, or false if the loop was unmodified. Unrolling
/// can only fail when the loop's latch block is not terminated by a conditional
@ -359,9 +398,13 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force,
"convergent operation.");
});
bool EpilogProfitability =
UnrollRuntimeEpilog.getNumOccurrences() ? UnrollRuntimeEpilog
: isEpilogProfitable(L);
if (RuntimeTripCount && TripMultiple % Count != 0 &&
!UnrollRuntimeLoopRemainder(L, Count, AllowExpensiveTripCount,
UnrollRuntimeEpilog, LI, SE, DT,
EpilogProfitability, LI, SE, DT,
PreserveLCSSA)) {
if (Force)
RuntimeTripCount = false;

6
test/Transforms/LoopUnroll/revisit.ll
View File

@ -138,11 +138,11 @@ l0.0.latch:
; CHECK-CHILDREN: LoopUnrollPass on Loop at depth 2 containing: %l0.0<header>
; CHECK-CHILDREN-NOT: LoopUnrollPass
;
; Revisit the children of the outer loop that are part of the prologue.
; Revisit the children of the outer loop that are part of the epilogue.
;
; CHECK: LoopUnrollPass on Loop at depth 2 containing: %l0.0.0.prol<header>
; CHECK: LoopUnrollPass on Loop at depth 2 containing: %l0.0.0.epil<header>
; CHECK-NOT: LoopUnrollPass
; CHECK: LoopUnrollPass on Loop at depth 2 containing: %l0.0.1.prol<header>
; CHECK: LoopUnrollPass on Loop at depth 2 containing: %l0.0.1.epil<header>
; CHECK-NOT: LoopUnrollPass
l0.latch:
br label %l0

7
test/Transforms/LoopUnroll/runtime-loop5.ll
View File

@ -14,9 +14,6 @@ entry:
%cmp1 = icmp eq i3 %n, 0
br i1 %cmp1, label %for.end, label %for.body
; UNROLL-16-NOT: for.body.prol:
; UNROLL-4: for.body.prol:
for.body: ; preds = %for.body, %entry
; UNROLL-16-LABEL: for.body:
; UNROLL-4-LABEL: for.body:
@ -42,6 +39,10 @@ for.body: ; preds = %for.body, %entry
; UNROLL-16-LABEL: for.end
; UNROLL-4-LABEL: for.end
; UNROLL-16-NOT: for.body.epil:
; UNROLL-4: for.body.epil:
for.end: ; preds = %for.body, %entry
%sum.0.lcssa = phi i3 [ 0, %entry ], [ %add, %for.body ]
ret i3 %sum.0.lcssa

4
test/Transforms/LoopUnroll/unroll-heuristics-pgo.ll
View File

@ -3,12 +3,12 @@
@known_constant = internal unnamed_addr constant [9 x i32] [i32 0, i32 -1, i32 0, i32 -1, i32 5, i32 -1, i32 0, i32 -1, i32 0], align 16
; CHECK-LABEL: @bar_prof
; CHECK: loop.prol:
; CHECK: loop:
; CHECK: %mul = mul
; CHECK: %mul.1 = mul
; CHECK: %mul.2 = mul
; CHECK: %mul.3 = mul
; CHECK: loop.epil:
define i32 @bar_prof(i32* noalias nocapture readonly %src, i64 %c) !prof !1 {
entry:
br label %loop
@ -32,7 +32,7 @@ loop.end:
}
; CHECK-LABEL: @bar_prof_flat
; CHECK-NOT: loop.prol
; CHECK-NOT: loop.epil
define i32 @bar_prof_flat(i32* noalias nocapture readonly %src, i64 %c) !prof !1 {
entry:
br label %loop

24
test/Transforms/LoopUnroll/unroll-pragmas.ll
View File

@ -171,10 +171,6 @@ for.end: ; preds = %for.body, %entry
; should be duplicated (original and 4x unrolled).
;
; CHECK-LABEL: @runtime_loop_with_count4(
; CHECK: for.body.prol:
; CHECK: store
; CHECK-NOT: store
; CHECK: br i1
; CHECK: for.body
; CHECK: store
; CHECK: store
@ -182,6 +178,10 @@ for.end: ; preds = %for.body, %entry
; CHECK: store
; CHECK-NOT: store
; CHECK: br i1
; CHECK: for.body.epil:
; CHECK: store
; CHECK-NOT: store
; CHECK: br i1
define void @runtime_loop_with_count4(i32* nocapture %a, i32 %b) {
entry:
%cmp3 = icmp sgt i32 %b, 0
@ -287,10 +287,6 @@ for.end: ; preds = %for.body
; (original and 8x).
;
; CHECK-LABEL: @runtime_loop_with_enable(
; CHECK: for.body.prol:
; CHECK: store
; CHECK-NOT: store
; CHECK: br i1
; CHECK: for.body:
; CHECK: store i32
; CHECK: store i32
@ -302,6 +298,10 @@ for.end: ; preds = %for.body
; CHECK: store i32
; CHECK-NOT: store i32
; CHECK: br i1
; CHECK: for.body.epil:
; CHECK: store
; CHECK-NOT: store
; CHECK: br i1
define void @runtime_loop_with_enable(i32* nocapture %a, i32 %b) {
entry:
%cmp3 = icmp sgt i32 %b, 0
@ -328,16 +328,16 @@ for.end: ; preds = %for.body, %entry
; should be duplicated (original and 3x unrolled).
;
; CHECK-LABEL: @runtime_loop_with_count3(
; CHECK: for.body.prol:
; CHECK: store
; CHECK-NOT: store
; CHECK: br i1
; CHECK: for.body
; CHECK: store
; CHECK: store
; CHECK: store
; CHECK-NOT: store
; CHECK: br i1
; CHECK: for.body.epil:
; CHECK: store
; CHECK-NOT: store
; CHECK: br i1
define void @runtime_loop_with_count3(i32* nocapture %a, i32 %b) {
entry:
%cmp3 = icmp sgt i32 %b, 0