llvm-6502/test/Transforms/PlaceSafepoints/finite-loops.ll
Sanjoy Das ead2d1fbe0 [Statepoints] Support for "patchable" statepoints.
Summary:
This change adds two new parameters to the statepoint intrinsic, `i64 id`
and `i32 num_patch_bytes`.  `id` gets propagated to the ID field
in the generated StackMap section.  If the `num_patch_bytes` is
non-zero then the statepoint is lowered to `num_patch_bytes` bytes of
nops instead of a call (the spill and reload code remains unchanged).
A non-zero `num_patch_bytes` is useful in situations where a language
runtime requires complete control over how a call is lowered.

This change brings statepoints one step closer to patchpoints.  With
some additional work (that is not part of this patch) it should be
possible to get rid of `TargetOpcode::STATEPOINT` altogether.

PlaceSafepoints generates `statepoint` wrappers with `id` set to
`0xABCDEF00` (the old default value for the ID reported in the stackmap)
and `num_patch_bytes` set to `0`.  This can be made more sophisticated
later.

Reviewers: reames, pgavlin, swaroop.sridhar, AndyAyers

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9546

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237214 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-12 23:52:24 +00:00

80 lines
1.7 KiB
LLVM

; Tests to ensure that we are not placing backedge safepoints in
; loops which are clearly finite.
;; RUN: opt %s -place-safepoints -S | FileCheck %s
; A simple counted loop with trivially known range
define void @test1(i32) gc "statepoint-example" {
; CHECK-LABEL: test1
; CHECK-LABEL: entry
; CHECK: statepoint
; CHECK-LABEL: loop
; CHECK-NOT: statepoint
entry:
br label %loop
loop:
%counter = phi i32 [ 0 , %entry ], [ %counter.inc , %loop ]
%counter.inc = add i32 %counter, 1
%counter.cmp = icmp slt i32 %counter.inc, 16
br i1 %counter.cmp, label %loop, label %exit
exit:
ret void
}
; The same counted loop, but with an unknown early exit
define void @test2(i32) gc "statepoint-example" {
; CHECK-LABEL: test2
; CHECK-LABEL: entry
; CHECK: statepoint
; CHECK-LABEL: loop
; CHECK-NOT: statepoint
entry:
br label %loop
loop:
%counter = phi i32 [ 0 , %entry ], [ %counter.inc , %continue ]
%counter.inc = add i32 %counter, 1
%counter.cmp = icmp slt i32 %counter.inc, 16
br i1 undef, label %continue, label %exit
continue:
br i1 %counter.cmp, label %loop, label %exit
exit:
ret void
}
; The range is a 8 bit value and we can't overflow
define void @test3(i8 %upper) gc "statepoint-example" {
; CHECK-LABEL: test3
; CHECK-LABEL: entry
; CHECK: statepoint
; CHECK-LABEL: loop
; CHECK-NOT: statepoint
entry:
br label %loop
loop:
%counter = phi i8 [ 0 , %entry ], [ %counter.inc , %loop ]
%counter.inc = add nsw i8 %counter, 1
%counter.cmp = icmp slt i8 %counter.inc, %upper
br i1 %counter.cmp, label %loop, label %exit
exit:
ret void
}
; This function is inlined when inserting a poll.
declare void @do_safepoint()
define void @gc.safepoint_poll() {
; CHECK-LABEL: gc.safepoint_poll
entry:
call void @do_safepoint()
ret void
}