[CallSiteSplitting] Refactor creating callsites.

Summary:
This change makes the call site creation more general if any of the
arguments is predicated on a condition in the call site's predecessors.

If we find a callsite, that potentially can be split, we collect the set
of conditions for the call site's predecessors (currently only 2
predecessors are allowed). To do that, we traverse each predecessor's
predecessors as long as it only has single predecessors and record the
condition, if it is relevant to the call site. For each condition, we
also check if the condition is taken or not. In case it is not taken,
we record the inverse predicate.

We use the recorded conditions to create the new call sites and split
the basic block.

This has 2 benefits: (1) it is slightly easier to see what is going on
(IMO) and (2) we can easily extend it to handle more complex control
flow.

Reviewers: davidxl, junbuml

Reviewed By: junbuml

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D40728

llvm-svn: 320547

1 files changed, 200 insertions, 0 deletions

diff --git a/llvm/test/Transforms/CallSiteSplitting/callsite-split-or-phi.ll b/llvm/test/Transforms/CallSiteSplitting/callsite-split-or-phi.ll
index 291c003acfe..e41a81f4b21 100644
--- a/llvm/test/Transforms/CallSiteSplitting/callsite-split-or-phi.ll
+++ b/llvm/test/Transforms/CallSiteSplitting/callsite-split-or-phi.ll
@@ -31,6 +31,64 @@ End:
   ret i32 %v
 }
 
+;CHECK-LABEL: @test_eq_eq_eq
+;CHECK-LABEL: Tail.predBB1.split:
+;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* null, i32 %v, i32 10)
+;CHECK-LABEL: Tail.predBB2.split:
+;CHECK: %[[CALL2:.*]] = call i32 @callee(i32* null, i32 1, i32 %p)
+;CHECK-LABEL: Tail
+;CHECK: %[[MERGED:.*]] = phi i32 [ %[[CALL1]], %Tail.predBB1.split ], [ %[[CALL2]], %Tail.predBB2.split ]
+;CHECK: ret i32 %[[MERGED]]
+define i32 @test_eq_eq_eq(i32* %a, i32 %v, i32 %p) {
+Header:
+  %tobool1 = icmp eq i32* %a, null
+  br i1 %tobool1, label %Header2, label %End
+
+Header2:
+  %tobool2 = icmp eq i32 %p, 10
+  br i1 %tobool2, label %Tail, label %TBB
+
+TBB:
+  %cmp = icmp eq i32 %v, 1
+  br i1 %cmp, label %Tail, label %End
+
+Tail:
+  %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
+  ret i32 %r
+
+End:
+  ret i32 %v
+}
+
+;CHECK-LABEL: @test_eq_eq_eq_constrain_same_i32_arg
+;CHECK-LABEL: Tail.predBB1.split:
+;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* %a, i32 222, i32 %p)
+;CHECK-LABEL: Tail.predBB2.split:
+;CHECK: %[[CALL2:.*]] = call i32 @callee(i32* %a, i32 333, i32 %p)
+;CHECK-LABEL: Tail
+;CHECK: %[[MERGED:.*]] = phi i32 [ %[[CALL1]], %Tail.predBB1.split ], [ %[[CALL2]], %Tail.predBB2.split ]
+;CHECK: ret i32 %[[MERGED]]
+define i32 @test_eq_eq_eq_constrain_same_i32_arg(i32* %a, i32 %v, i32 %p) {
+Header:
+  %tobool1 = icmp eq i32 %v, 111
+  br i1 %tobool1, label %Header2, label %End
+
+Header2:
+  %tobool2 = icmp eq i32 %v, 222
+  br i1 %tobool2, label %Tail, label %TBB
+
+TBB:
+  %cmp = icmp eq i32 %v, 333
+  br i1 %cmp, label %Tail, label %End
+
+Tail:
+  %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
+  ret i32 %r
+
+End:
+  ret i32 %v
+}
+
 ;CHECK-LABEL: @test_ne_eq
 ;CHECK-LABEL: Tail.predBB1.split:
 ;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* nonnull %a, i32 %v, i32 1)
@@ -58,6 +116,35 @@ End:
   ret i32 %v
 }
 
+;CHECK-LABEL: @test_ne_eq_ne
+;CHECK-LABEL: Tail.predBB1.split:
+;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* nonnull %a, i32 %v, i32 10)
+;CHECK-LABEL: Tail.predBB2.split:
+;CHECK: %[[CALL2:.*]] = call i32 @callee(i32* nonnull %a, i32 %v, i32 %p)
+;CHECK-LABEL: Tail
+;CHECK: %[[MERGED:.*]] = phi i32 [ %[[CALL1]], %Tail.predBB1.split ], [ %[[CALL2]], %Tail.predBB2.split ]
+;CHECK: ret i32 %[[MERGED]]
+define i32 @test_ne_eq_ne(i32* %a, i32 %v, i32 %p) {
+Header:
+  %tobool1 = icmp ne i32* %a, null
+  br i1 %tobool1, label %Header2, label %End
+
+Header2:
+  %tobool2 = icmp eq i32 %p, 10
+  br i1 %tobool2, label %Tail, label %TBB
+
+TBB:
+  %cmp = icmp ne i32 %v, 1
+  br i1 %cmp, label %Tail, label %End
+
+Tail:
+  %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
+  ret i32 %r
+
+End:
+  ret i32 %v
+}
+
 ;CHECK-LABEL: @test_ne_ne
 ;CHECK-LABEL: Tail.predBB1.split:
 ;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* nonnull %a, i32 %v, i32 1)
@@ -85,6 +172,37 @@ End:
   ret i32 %v
 }
 
+;CHECK-LABEL: @test_ne_ne_ne_constrain_same_pointer_arg
+;CHECK-LABEL: Tail.predBB1.split:
+;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* nonnull %a, i32 %v, i32 %p)
+;CHECK-LABEL: Tail.predBB2.split:
+;CHECK: %[[CALL2:.*]] = call i32 @callee(i32* nonnull %a, i32 %v, i32 %p)
+;CHECK-LABEL: Tail
+;CHECK: %[[MERGED:.*]] = phi i32 [ %[[CALL1]], %Tail.predBB1.split ], [ %[[CALL2]], %Tail.predBB2.split ]
+;CHECK: ret i32 %[[MERGED]]
+define i32 @test_ne_ne_ne_constrain_same_pointer_arg(i32* %a, i32 %v, i32 %p, i32* %a2, i32* %a3) {
+Header:
+  %tobool1 = icmp ne i32* %a, null
+  br i1 %tobool1, label %Header2, label %End
+
+Header2:
+  %tobool2 = icmp ne i32* %a, %a2
+  br i1 %tobool2, label %Tail, label %TBB
+
+TBB:
+  %cmp = icmp ne i32* %a, %a3
+  br i1 %cmp, label %Tail, label %End
+
+Tail:
+  %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
+  ret i32 %r
+
+End:
+  ret i32 %v
+}
+
+
+
 ;CHECK-LABEL: @test_eq_eq_untaken
 ;CHECK-LABEL: Tail.predBB1.split:
 ;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* nonnull %a, i32 %v, i32 1)
@@ -112,6 +230,35 @@ End:
   ret i32 %v
 }
 
+;CHECK-LABEL: @test_eq_eq_eq_untaken
+;CHECK-LABEL: Tail.predBB1.split:
+;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* nonnull %a, i32 %v, i32 10)
+;CHECK-LABEL: Tail.predBB2.split:
+;CHECK: %[[CALL2:.*]] = call i32 @callee(i32* nonnull %a, i32 1, i32 %p)
+;CHECK-LABEL: Tail
+;CHECK: %[[MERGED:.*]] = phi i32 [ %[[CALL1]], %Tail.predBB1.split ], [ %[[CALL2]], %Tail.predBB2.split ]
+;CHECK: ret i32 %[[MERGED]]
+define i32 @test_eq_eq_eq_untaken(i32* %a, i32 %v, i32 %p) {
+Header:
+  %tobool1 = icmp eq i32* %a, null
+  br i1 %tobool1, label %End, label %Header2
+
+Header2:
+  %tobool2 = icmp eq i32 %p, 10
+  br i1 %tobool2, label %Tail, label %TBB
+
+TBB:
+  %cmp = icmp eq i32 %v, 1
+  br i1 %cmp, label %Tail, label %End
+
+Tail:
+  %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
+  ret i32 %r
+
+End:
+  ret i32 %v
+}
+
 ;CHECK-LABEL: @test_ne_eq_untaken
 ;CHECK-LABEL: Tail.predBB1.split:
 ;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* null, i32 %v, i32 1)
@@ -139,6 +286,35 @@ End:
   ret i32 %v
 }
 
+;CHECK-LABEL: @test_ne_eq_ne_untaken
+;CHECK-LABEL: Tail.predBB1.split:
+;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* null, i32 %v, i32 10)
+;CHECK-LABEL: Tail.predBB2.split:
+;CHECK: %[[CALL2:.*]] = call i32 @callee(i32* null, i32 %v, i32 %p)
+;CHECK-LABEL: Tail
+;CHECK: %[[MERGED:.*]] = phi i32 [ %[[CALL1]], %Tail.predBB1.split ], [ %[[CALL2]], %Tail.predBB2.split ]
+;CHECK: ret i32 %[[MERGED]]
+define i32 @test_ne_eq_ne_untaken(i32* %a, i32 %v, i32 %p) {
+Header:
+  %tobool1 = icmp ne i32* %a, null
+  br i1 %tobool1, label %End, label %Header2
+
+Header2:
+  %tobool2 = icmp eq i32 %p, 10
+  br i1 %tobool2, label %Tail, label %TBB
+
+TBB:
+  %cmp = icmp ne i32 %v, 1
+  br i1 %cmp, label %Tail, label %End
+
+Tail:
+  %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
+  ret i32 %r
+
+End:
+  ret i32 %v
+}
+
 ;CHECK-LABEL: @test_ne_ne_untaken
 ;CHECK-LABEL: Tail.predBB1.split:
 ;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* null, i32 %v, i32 1)
@@ -342,6 +518,30 @@ End:
   ret i32 %v
 }
 
+;CHECK-LABEL: @test_unreachable
+;CHECK-LABEL: Tail.predBB1.split:
+;CHECK: %[[CALL1:.*]] = call i32 @callee(i32* %a, i32 %v, i32 10)
+;CHECK-LABEL: Tail.predBB2.split:
+;CHECK: %[[CALL2:.*]] = call i32 @callee(i32* %a, i32 1, i32 %p)
+;CHECK-LABEL: Tail
+;CHECK: %[[MERGED:.*]] = phi i32 [ %[[CALL1]], %Tail.predBB1.split ], [ %[[CALL2]], %Tail.predBB2.split ]
+;CHECK: ret i32 %[[MERGED]]
+define i32 @test_unreachable(i32* %a, i32 %v, i32 %p) {
+Entry:
+  br label %End
+Header:
+  %tobool2 = icmp eq i32 %p, 10
+  br i1 %tobool2, label %Tail, label %TBB
+TBB:
+  %cmp = icmp eq i32 %v, 1
+  br i1 %cmp, label %Tail, label %Header
+Tail:
+  %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
+  ret i32 %r
+End:
+  ret i32 %v
+}
+
 define i32 @callee(i32* %a, i32 %v, i32 %p) {
 entry:
   %c = icmp ne i32* %a, null