Revert revision 171524. Original message:

URL: http://llvm.org/viewvc/llvm-project?rev=171524&view=rev
Log:
The current Intel Atom microarchitecture has a feature whereby when a function
returns early then it is slightly faster to execute a sequence of NOP
instructions to wait until the return address is ready,
as opposed to simply stalling on the ret instruction
until the return address is ready.

When compiling for X86 Atom only, this patch will run a pass, called
"X86PadShortFunction" which will add NOP instructions where less than four
cycles elapse between function entry and return.

It includes tests.

Patch by Andy Zhang.

llvm-svn: 171603

1 files changed, 0 insertions, 71 deletions

diff --git a/llvm/test/CodeGen/X86/atom-pad-short-functions.ll b/llvm/test/CodeGen/X86/atom-pad-short-functions.ll
deleted file mode 100644
index 3e599345970..00000000000
--- a/llvm/test/CodeGen/X86/atom-pad-short-functions.ll
+++ /dev/null
@@ -1,71 +0,0 @@
-; RUN: llc < %s -mcpu=atom -mtriple=i686-linux  | FileCheck %s
-
-declare void @external_function(...)
-
-define i32 @test_return_val(i32 %a) nounwind {
-; CHECK: test_return_val
-; CHECK: movl
-; CHECK: nop
-; CHECK: nop
-; CHECK: nop
-; CHECK: nop
-; CHECK: nop
-; CHECK: nop
-; CHECK: ret
-  ret i32 %a
-}
-
-define i32 @test_add(i32 %a, i32 %b) nounwind {
-; CHECK: test_add
-; CHECK: addl
-; CHECK: nop
-; CHECK: nop
-; CHECK: nop
-; CHECK: nop
-; CHECK: ret
-  %result = add i32 %a, %b
-  ret i32 %result
-}
-
-define i32 @test_multiple_ret(i32 %a, i32 %b, i1 %c) nounwind {
-; CHECK: @test_multiple_ret
-; CHECK: je
-
-; CHECK: nop
-; CHECK: nop
-; CHECK: ret
-
-; CHECK: nop
-; CHECK: nop
-; CHECK: ret
-
-  br i1 %c, label %bb1, label %bb2
-
-bb1:
-  ret i32 %a
-
-bb2:
-  ret i32 %b
-}
-
-define void @test_call_others(i32 %x) nounwind
-{
-; CHECK: test_call_others
-; CHECK: je
-  %tobool = icmp eq i32 %x, 0
-  br i1 %tobool, label %if.end, label %true.case
-
-; CHECK: jmp external_function
-true.case:
-  tail call void bitcast (void (...)* @external_function to void ()*)() nounwind
-  br label %if.end
-
-; CHECK: nop
-; CHECK: nop
-; CHECK: nop
-; CHECK: nop
-; CHECK: ret
-if.end:
-  ret void
-
-}