Introduce more tests for PlaceSafepoints

These tests the two optimizations for backedge insertion currently implemented and the split backedge flag which is currently off by default.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228617 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/PlaceSafepoints/call-in-loop.ll

@@ -0,0 +1,31 @@
+; If there's a call in the loop which dominates the backedge, we 
+; don't need a safepoint poll (since the callee must contain a 
+; poll test).
+;; RUN: opt %s -place-safepoints -S | FileCheck %s
+
+declare void @foo()
+
+define void @test1() {
+; CHECK-LABEL: test1
+
+entry:
+; CHECK-LABEL: entry
+; CHECK: statepoint
+  br label %loop
+
+loop:
+; CHECK-LABEL: loop
+; CHECK: @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @foo
+; CHECK-NOT: statepoint
+  call void @foo()
+  br label %loop
+}
+
+; 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
+}

test/Transforms/PlaceSafepoints/finite-loops.ll

@@ -0,0 +1,80 @@
+; 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) {
+; 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) {
+; 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) {
+; 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
+}

test/Transforms/PlaceSafepoints/split-backedge.ll

@@ -0,0 +1,46 @@
+;; A very basic test to make sure that splitting the backedge keeps working
+;; RUN: opt -place-safepoints -spp-split-backedge=1 -S %s | FileCheck %s
+
+define void @test(i32, i1 %cond) {
+; CHECK-LABEL: @test
+; CHECK-LABEL: loop.loop_crit_edge
+; CHECK: gc.statepoint
+; CHECK-NEXT: br label %loop
+entry:
+  br label %loop
+
+loop:
+  br i1 %cond, label %loop, label %exit
+
+exit:
+  ret void
+}
+
+; Test for the case where a single conditional branch jumps to two
+; different loop header blocks.  Since we're currently using LoopSimplfy
+; this doesn't hit the interesting case, but once we remove that, we need
+; to be sure this keeps working.
+define void @test2(i32, i1 %cond) {
+; CHECK-LABEL: @test2
+; CHECK-LABE: loop.loopexit.split
+; CHECK: gc.statepoint
+; CHECK-NEXT: br label %loop
+; CHECK-LABEL: loop2.loop2_crit_edge
+; CHECK: gc.statepoint
+; CHECK-NEXT: br label %loop2
+entry:
+  br label %loop
+
+loop:
+  br label %loop2
+
+loop2:
+  br i1 %cond, label %loop, label %loop2
+}
+
+declare void @do_safepoint()
+define void @gc.safepoint_poll() {
+entry:
+  call void @do_safepoint()
+  ret void
+}