Backport of rL326666 and rL326668 for PR36607 and PR36608.

[CallSiteSplitting] properly split musttail calls.

The original author was Fedor Indutny <fedor@indutny.com>.

`musttail` calls can't be naively splitted. The split blocks must
include not only the call instruction itself, but also (optional)
`bitcast` and `return` instructions that follow it.

Clone `bitcast` and `ret`, place them into the split blocks, and
remove the tail block when done.

Reviewers: junbuml, mcrosier, davidxl, davide, fhahn

Reviewed By: fhahn

Subscribers: JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D43729


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@329793 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 109 insertions, 0 deletions

diff --git a/test/Transforms/CallSiteSplitting/musttail.ll b/test/Transforms/CallSiteSplitting/musttail.ll
new file mode 100644
index 00000000000..97548501cd5
--- /dev/null
+++ b/test/Transforms/CallSiteSplitting/musttail.ll
@@ -0,0 +1,109 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -callsite-splitting -S | FileCheck %s
+
+define i8* @caller(i8* %a, i8* %b) {
+; CHECK-LABEL: @caller(
+; CHECK-NEXT:  Top:
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i8* [[A:%.*]], null
+; CHECK-NEXT:    br i1 [[C]], label [[TAIL_PREDBB1_SPLIT:%.*]], label [[TBB:%.*]]
+; CHECK:       TBB:
+; CHECK-NEXT:    [[C2:%.*]] = icmp eq i8* [[B:%.*]], null
+; CHECK-NEXT:    br i1 [[C2]], label [[TAIL_PREDBB2_SPLIT:%.*]], label [[END:%.*]]
+; CHECK:       Tail.predBB1.split:
+; CHECK-NEXT:    [[TMP0:%.*]] = musttail call i8* @callee(i8* null, i8* [[B]])
+; CHECK-NEXT:    [[CB1:%.*]] = bitcast i8* [[TMP0]] to i8*
+; CHECK-NEXT:    ret i8* [[CB1]]
+; CHECK:       Tail.predBB2.split:
+; CHECK-NEXT:    [[TMP1:%.*]] = musttail call i8* @callee(i8* nonnull [[A]], i8* null)
+; CHECK-NEXT:    [[CB2:%.*]] = bitcast i8* [[TMP1]] to i8*
+; CHECK-NEXT:    ret i8* [[CB2]]
+; CHECK:       End:
+; CHECK-NEXT:    ret i8* null
+;
+Top:
+  %c = icmp eq i8* %a, null
+  br i1 %c, label %Tail, label %TBB
+TBB:
+  %c2 = icmp eq i8* %b, null
+  br i1 %c2, label %Tail, label %End
+Tail:
+  %ca = musttail call i8* @callee(i8* %a, i8* %b)
+  %cb = bitcast i8* %ca to i8*
+  ret i8* %cb
+End:
+  ret i8* null
+}
+
+define i8* @callee(i8* %a, i8* %b) noinline {
+; CHECK-LABEL: define i8* @callee(
+; CHECK-NEXT:    ret i8* [[A:%.*]]
+;
+  ret i8* %a
+}
+
+define i8* @no_cast_caller(i8* %a, i8* %b) {
+; CHECK-LABEL: @no_cast_caller(
+; CHECK-NEXT:  Top:
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i8* [[A:%.*]], null
+; CHECK-NEXT:    br i1 [[C]], label [[TAIL_PREDBB1_SPLIT:%.*]], label [[TBB:%.*]]
+; CHECK:       TBB:
+; CHECK-NEXT:    [[C2:%.*]] = icmp eq i8* [[B:%.*]], null
+; CHECK-NEXT:    br i1 [[C2]], label [[TAIL_PREDBB2_SPLIT:%.*]], label [[END:%.*]]
+; CHECK:       Tail.predBB1.split:
+; CHECK-NEXT:    [[TMP0:%.*]] = musttail call i8* @callee(i8* null, i8* [[B]])
+; CHECK-NEXT:    ret i8* [[TMP0]]
+; CHECK:       Tail.predBB2.split:
+; CHECK-NEXT:    [[TMP1:%.*]] = musttail call i8* @callee(i8* nonnull [[A]], i8* null)
+; CHECK-NEXT:    ret i8* [[TMP1]]
+; CHECK:       End:
+; CHECK-NEXT:    ret i8* null
+;
+Top:
+  %c = icmp eq i8* %a, null
+  br i1 %c, label %Tail, label %TBB
+TBB:
+  %c2 = icmp eq i8* %b, null
+  br i1 %c2, label %Tail, label %End
+Tail:
+  %ca = musttail call i8* @callee(i8* %a, i8* %b)
+  ret i8* %ca
+End:
+  ret i8* null
+}
+
+define void @void_caller(i8* %a, i8* %b) {
+; CHECK-LABEL: @void_caller(
+; CHECK-NEXT:  Top:
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i8* [[A:%.*]], null
+; CHECK-NEXT:    br i1 [[C]], label [[TAIL_PREDBB1_SPLIT:%.*]], label [[TBB:%.*]]
+; CHECK:       TBB:
+; CHECK-NEXT:    [[C2:%.*]] = icmp eq i8* [[B:%.*]], null
+; CHECK-NEXT:    br i1 [[C2]], label [[TAIL_PREDBB2_SPLIT:%.*]], label [[END:%.*]]
+; CHECK:       Tail.predBB1.split:
+; CHECK-NEXT:    musttail call void @void_callee(i8* null, i8* [[B]])
+; CHECK-NEXT:    ret void
+; CHECK:       Tail.predBB2.split:
+; CHECK-NEXT:    musttail call void @void_callee(i8* nonnull [[A]], i8* null)
+; CHECK-NEXT:    ret void
+; CHECK:       End:
+; CHECK-NEXT:    ret void
+;
+Top:
+  %c = icmp eq i8* %a, null
+  br i1 %c, label %Tail, label %TBB
+TBB:
+  %c2 = icmp eq i8* %b, null
+  br i1 %c2, label %Tail, label %End
+Tail:
+  musttail call void @void_callee(i8* %a, i8* %b)
+  ret void
+End:
+  ret void
+}
+
+define void @void_callee(i8* %a, i8* %b) noinline {
+; CHECK-LABEL: define void @void_callee(
+; CHECK-NEXT:    ret void
+;
+  ret void
+}