Add documentation on sibling call optimization. Rename tailcall2.ll test to sibcall.ll.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97980 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 218 insertions, 0 deletions

diff --git a/test/CodeGen/X86/sibcall.ll b/test/CodeGen/X86/sibcall.ll
new file mode 100644
index 0000000000..90315fd2f2
--- /dev/null
+++ b/test/CodeGen/X86/sibcall.ll
@@ -0,0 +1,218 @@
+; RUN: llc < %s -march=x86    -asm-verbose=false | FileCheck %s -check-prefix=32
+; RUN: llc < %s -march=x86-64 -asm-verbose=false | FileCheck %s -check-prefix=64
+
+define void @t1(i32 %x) nounwind ssp {
+entry:
+; 32: t1:
+; 32: jmp {{_?}}foo
+
+; 64: t1:
+; 64: jmp {{_?}}foo
+  tail call void @foo() nounwind
+  ret void
+}
+
+declare void @foo()
+
+define void @t2() nounwind ssp {
+entry:
+; 32: t2:
+; 32: jmp {{_?}}foo2
+
+; 64: t2:
+; 64: jmp {{_?}}foo2
+  %0 = tail call i32 @foo2() nounwind
+  ret void
+}
+
+declare i32 @foo2()
+
+define void @t3() nounwind ssp {
+entry:
+; 32: t3:
+; 32: jmp {{_?}}foo3
+
+; 64: t3:
+; 64: jmp {{_?}}foo3
+  %0 = tail call i32 @foo3() nounwind
+  ret void
+}
+
+declare i32 @foo3()
+
+define void @t4(void (i32)* nocapture %x) nounwind ssp {
+entry:
+; 32: t4:
+; 32: call *
+; FIXME: gcc can generate a tailcall for this. But it's tricky.
+
+; 64: t4:
+; 64-NOT: call
+; 64: jmpq *
+  tail call void %x(i32 0) nounwind
+  ret void
+}
+
+define void @t5(void ()* nocapture %x) nounwind ssp {
+entry:
+; 32: t5:
+; 32-NOT: call
+; 32: jmpl *
+
+; 64: t5:
+; 64-NOT: call
+; 64: jmpq *
+  tail call void %x() nounwind
+  ret void
+}
+
+define i32 @t6(i32 %x) nounwind ssp {
+entry:
+; 32: t6:
+; 32: call {{_?}}t6
+; 32: jmp {{_?}}bar
+
+; 64: t6:
+; 64: jmp {{_?}}t6
+; 64: jmp {{_?}}bar
+  %0 = icmp slt i32 %x, 10
+  br i1 %0, label %bb, label %bb1
+
+bb:
+  %1 = add nsw i32 %x, -1
+  %2 = tail call i32 @t6(i32 %1) nounwind ssp
+  ret i32 %2
+
+bb1:
+  %3 = tail call i32 @bar(i32 %x) nounwind
+  ret i32 %3
+}
+
+declare i32 @bar(i32)
+
+define i32 @t7(i32 %a, i32 %b, i32 %c) nounwind ssp {
+entry:
+; 32: t7:
+; 32: jmp {{_?}}bar2
+
+; 64: t7:
+; 64: jmp {{_?}}bar2
+  %0 = tail call i32 @bar2(i32 %a, i32 %b, i32 %c) nounwind
+  ret i32 %0
+}
+
+declare i32 @bar2(i32, i32, i32)
+
+define signext i16 @t8() nounwind ssp {
+entry:
+; 32: t8:
+; 32: call {{_?}}bar3
+
+; 64: t8:
+; 64: callq {{_?}}bar3
+  %0 = tail call signext i16 @bar3() nounwind      ; <i16> [#uses=1]
+  ret i16 %0
+}
+
+declare signext i16 @bar3()
+
+define signext i16 @t9(i32 (i32)* nocapture %x) nounwind ssp {
+entry:
+; 32: t9:
+; 32: call *
+
+; 64: t9:
+; 64: callq *
+  %0 = bitcast i32 (i32)* %x to i16 (i32)*
+  %1 = tail call signext i16 %0(i32 0) nounwind
+  ret i16 %1
+}
+
+define void @t10() nounwind ssp {
+entry:
+; 32: t10:
+; 32: call
+
+; 64: t10:
+; 64: callq
+  %0 = tail call i32 @foo4() noreturn nounwind
+  unreachable
+}
+
+declare i32 @foo4()
+
+define i32 @t11(i32 %x, i32 %y, i32 %z.0, i32 %z.1, i32 %z.2) nounwind ssp {
+; In 32-bit mode, it's emitting a bunch of dead loads that are not being
+; eliminated currently.
+
+; 32: t11:
+; 32-NOT: subl ${{[0-9]+}}, %esp
+; 32: jne
+; 32-NOT: movl
+; 32-NOT: addl ${{[0-9]+}}, %esp
+; 32: jmp {{_?}}foo5
+
+; 64: t11:
+; 64-NOT: subq ${{[0-9]+}}, %esp
+; 64-NOT: addq ${{[0-9]+}}, %esp
+; 64: jmp {{_?}}foo5
+entry:
+  %0 = icmp eq i32 %x, 0
+  br i1 %0, label %bb6, label %bb
+
+bb:
+  %1 = tail call i32 @foo5(i32 %x, i32 %y, i32 %z.0, i32 %z.1, i32 %z.2) nounwind
+  ret i32 %1
+
+bb6:
+  ret i32 0
+}
+
+declare i32 @foo5(i32, i32, i32, i32, i32)
+
+%struct.t = type { i32, i32, i32, i32, i32 }
+
+define i32 @t12(i32 %x, i32 %y, %struct.t* byval align 4 %z) nounwind ssp {
+; 32: t12:
+; 32-NOT: subl ${{[0-9]+}}, %esp
+; 32-NOT: addl ${{[0-9]+}}, %esp
+; 32: jmp {{_?}}foo6
+
+; 64: t12:
+; 64-NOT: subq ${{[0-9]+}}, %esp
+; 64-NOT: addq ${{[0-9]+}}, %esp
+; 64: jmp {{_?}}foo6
+entry:
+  %0 = icmp eq i32 %x, 0
+  br i1 %0, label %bb2, label %bb
+
+bb:
+  %1 = tail call i32 @foo6(i32 %x, i32 %y, %struct.t* byval align 4 %z) nounwind
+  ret i32 %1
+
+bb2:
+  ret i32 0
+}
+
+declare i32 @foo6(i32, i32, %struct.t* byval align 4)
+
+; rdar://r7717598
+%struct.ns = type { i32, i32 }
+%struct.cp = type { float, float }
+
+define %struct.ns* @t13(%struct.cp* %yy) nounwind ssp {
+; 32: t13:
+; 32-NOT: jmp
+; 32: call
+; 32: ret
+
+; 64: t13:
+; 64-NOT: jmp
+; 64: call
+; 64: ret
+entry:
+  %0 = tail call fastcc %struct.ns* @foo7(%struct.cp* byval align 4 %yy, i8 signext 0) nounwind
+  ret %struct.ns* %0
+}
+
+declare fastcc %struct.ns* @foo7(%struct.cp* byval align 4, i8 signext) nounwind ssp