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llvm-mirror/test/Transforms/SimpleLoopUnswitch/update-scev.ll
Alina Sbirlea 1542bebc55 [LoopPassManager + MemorySSA] Only enable use of MemorySSA for LPMs known to preserve it.
Summary:
Add a flag to the FunctionToLoopAdaptor that allows enabling MemorySSA only for the loop pass managers that are known to preserve it.

If an LPM is known to have only loop transforms that *all* preserve MemorySSA, then use MemorySSA if `EnableMSSALoopDependency` is set.
If an LPM has loop passes that do not preserve MemorySSA, then the flag passed is `false`, regardless of the value of `EnableMSSALoopDependency`.

When using a custom loop pass pipeline via `passes=...`, use keyword `loop` vs `loop-mssa` to use MemorySSA in that LPM. If a loop that does not preserve MemorySSA is added while using the `loop-mssa` keyword, that's an error.

Add the new `loop-mssa` keyword to a few tests where a difference occurs when enabling MemorySSA.

Reviewers: chandlerc

Subscribers: mehdi_amini, Prazek, george.burgess.iv, sanjoy.google, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66376

llvm-svn: 369548
2019-08-21 17:00:57 +00:00

188 lines
6.6 KiB
LLVM

; RUN: opt -passes='print<scalar-evolution>,loop(unswitch<nontrivial>,loop-instsimplify),print<scalar-evolution>' -S < %s 2>%t.scev | FileCheck %s
; RUN: opt -verify-memoryssa -passes='print<scalar-evolution>,loop-mssa(unswitch<nontrivial>,loop-instsimplify),print<scalar-evolution>' -S < %s 2>%t.scev | FileCheck %s
; RUN: FileCheck %s --check-prefix=SCEV < %t.scev
target triple = "x86_64-unknown-linux-gnu"
declare void @f()
; Check that trivially unswitching an inner loop resets both the inner and outer
; loop trip count.
define void @test1(i32 %n, i32 %m, i1 %cond) {
; Check that SCEV has no trip count before unswitching.
; SCEV-LABEL: Determining loop execution counts for: @test1
; SCEV: Loop %inner_loop_begin: <multiple exits> Unpredictable backedge-taken count.
; SCEV: Loop %outer_loop_begin: Unpredictable backedge-taken count.
;
; Now check that after unswitching and simplifying instructions we get clean
; backedge-taken counts.
; SCEV-LABEL: Determining loop execution counts for: @test1
; SCEV: Loop %inner_loop_begin: backedge-taken count is (-1 + (1 smax %m))<nsw>
; SCEV: Loop %outer_loop_begin: backedge-taken count is (-1 + (1 smax %n))<nsw>
;
; And verify the code matches what we expect.
; CHECK-LABEL: define void @test1(
entry:
br label %outer_loop_begin
; Ensure the outer loop didn't get unswitched.
; CHECK: entry:
; CHECK-NEXT: br label %outer_loop_begin
outer_loop_begin:
%i = phi i32 [ %i.next, %outer_loop_latch ], [ 0, %entry ]
; Block unswitching of the outer loop with a noduplicate call.
call void @f() noduplicate
br label %inner_loop_begin
; Ensure the inner loop got unswitched into the outer loop.
; CHECK: outer_loop_begin:
; CHECK-NEXT: %{{.*}} = phi i32
; CHECK-NEXT: call void @f()
; CHECK-NEXT: br i1 %cond,
inner_loop_begin:
%j = phi i32 [ %j.next, %inner_loop_latch ], [ 0, %outer_loop_begin ]
br i1 %cond, label %inner_loop_latch, label %inner_loop_early_exit
inner_loop_latch:
%j.next = add nsw i32 %j, 1
%j.cmp = icmp slt i32 %j.next, %m
br i1 %j.cmp, label %inner_loop_begin, label %inner_loop_late_exit
inner_loop_early_exit:
%j.lcssa = phi i32 [ %i, %inner_loop_begin ]
br label %outer_loop_latch
inner_loop_late_exit:
br label %outer_loop_latch
outer_loop_latch:
%i.phi = phi i32 [ %j.lcssa, %inner_loop_early_exit ], [ %i, %inner_loop_late_exit ]
%i.next = add nsw i32 %i.phi, 1
%i.cmp = icmp slt i32 %i.next, %n
br i1 %i.cmp, label %outer_loop_begin, label %exit
exit:
ret void
}
; Check that trivially unswitching an inner loop resets both the inner and outer
; loop trip count.
define void @test2(i32 %n, i32 %m, i32 %cond) {
; Check that SCEV has no trip count before unswitching.
; SCEV-LABEL: Determining loop execution counts for: @test2
; SCEV: Loop %inner_loop_begin: <multiple exits> Unpredictable backedge-taken count.
; SCEV: Loop %outer_loop_begin: Unpredictable backedge-taken count.
;
; Now check that after unswitching and simplifying instructions we get clean
; backedge-taken counts.
; SCEV-LABEL: Determining loop execution counts for: @test2
; SCEV: Loop %inner_loop_begin: backedge-taken count is (-1 + (1 smax %m))<nsw>
; SCEV: Loop %outer_loop_begin: backedge-taken count is (-1 + (1 smax %n))<nsw>
;
; CHECK-LABEL: define void @test2(
entry:
br label %outer_loop_begin
; Ensure the outer loop didn't get unswitched.
; CHECK: entry:
; CHECK-NEXT: br label %outer_loop_begin
outer_loop_begin:
%i = phi i32 [ %i.next, %outer_loop_latch ], [ 0, %entry ]
; Block unswitching of the outer loop with a noduplicate call.
call void @f() noduplicate
br label %inner_loop_begin
; Ensure the inner loop got unswitched into the outer loop.
; CHECK: outer_loop_begin:
; CHECK-NEXT: %{{.*}} = phi i32
; CHECK-NEXT: call void @f()
; CHECK-NEXT: switch i32 %cond,
inner_loop_begin:
%j = phi i32 [ %j.next, %inner_loop_latch ], [ 0, %outer_loop_begin ]
switch i32 %cond, label %inner_loop_early_exit [
i32 1, label %inner_loop_latch
i32 2, label %inner_loop_latch
]
inner_loop_latch:
%j.next = add nsw i32 %j, 1
%j.cmp = icmp slt i32 %j.next, %m
br i1 %j.cmp, label %inner_loop_begin, label %inner_loop_late_exit
inner_loop_early_exit:
%j.lcssa = phi i32 [ %i, %inner_loop_begin ]
br label %outer_loop_latch
inner_loop_late_exit:
br label %outer_loop_latch
outer_loop_latch:
%i.phi = phi i32 [ %j.lcssa, %inner_loop_early_exit ], [ %i, %inner_loop_late_exit ]
%i.next = add nsw i32 %i.phi, 1
%i.cmp = icmp slt i32 %i.next, %n
br i1 %i.cmp, label %outer_loop_begin, label %exit
exit:
ret void
}
; Check that non-trivial unswitching of a branch in an inner loop into the outer
; loop invalidates both inner and outer.
define void @test3(i32 %n, i32 %m, i1 %cond) {
; Check that SCEV has no trip count before unswitching.
; SCEV-LABEL: Determining loop execution counts for: @test3
; SCEV: Loop %inner_loop_begin: <multiple exits> Unpredictable backedge-taken count.
; SCEV: Loop %outer_loop_begin: Unpredictable backedge-taken count.
;
; Now check that after unswitching and simplifying instructions we get clean
; backedge-taken counts.
; SCEV-LABEL: Determining loop execution counts for: @test3
; SCEV: Loop %inner_loop_begin{{.*}}: backedge-taken count is (-1 + (1 smax %m))<nsw>
; SCEV: Loop %outer_loop_begin: backedge-taken count is (-1 + (1 smax %n))<nsw>
;
; And verify the code matches what we expect.
; CHECK-LABEL: define void @test3(
entry:
br label %outer_loop_begin
; Ensure the outer loop didn't get unswitched.
; CHECK: entry:
; CHECK-NEXT: br label %outer_loop_begin
outer_loop_begin:
%i = phi i32 [ %i.next, %outer_loop_latch ], [ 0, %entry ]
; Block unswitching of the outer loop with a noduplicate call.
call void @f() noduplicate
br label %inner_loop_begin
; Ensure the inner loop got unswitched into the outer loop.
; CHECK: outer_loop_begin:
; CHECK-NEXT: %{{.*}} = phi i32
; CHECK-NEXT: call void @f()
; CHECK-NEXT: br i1 %cond,
inner_loop_begin:
%j = phi i32 [ %j.next, %inner_loop_latch ], [ 0, %outer_loop_begin ]
%j.tmp = add nsw i32 %j, 1
br i1 %cond, label %inner_loop_latch, label %inner_loop_early_exit
inner_loop_latch:
%j.next = add nsw i32 %j, 1
%j.cmp = icmp slt i32 %j.next, %m
br i1 %j.cmp, label %inner_loop_begin, label %inner_loop_late_exit
inner_loop_early_exit:
%j.lcssa = phi i32 [ %j.tmp, %inner_loop_begin ]
br label %outer_loop_latch
inner_loop_late_exit:
br label %outer_loop_latch
outer_loop_latch:
%inc.phi = phi i32 [ %j.lcssa, %inner_loop_early_exit ], [ 1, %inner_loop_late_exit ]
%i.next = add nsw i32 %i, %inc.phi
%i.cmp = icmp slt i32 %i.next, %n
br i1 %i.cmp, label %outer_loop_begin, label %exit
exit:
ret void
}