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llvm-mirror/test/Transforms/Inline/vector-bonus.ll
Chandler Carruth aeb0ec68a8 [inliner] Fix the early-exit of the inline cost analysis to correctly
model the dense vector instruction bonuses.

Previously, this code really didn't effectively compute the density of
inlined vector instructions and apply the intended inliner bonus. It
would try to compute it repeatedly while analyzing the function and
didn't handle the case where future vector instructions would tip the
scales back towards the bonus.

Instead, speculatively apply all possible bonuses to the threshold
initially. Once we *know* that a certain bonus can not be applied,
subtract it. This should delay early bailout enough to get much more
consistent results without actually causing us to analyze huge swaths of
code. I expect some (hopefully mild) compile time hit here, and some
swings in performance, but this was definitely the intended behavior of
these bonuses.

This also dramatically simplifies the computation of the bonuses to not
interact with each other in confusing ways. The previous code didn't do
a good job of this and the values for bonuses may be surprising but are
at least now clearly written in the code.

Finally, fix code to be in line with comments and use zero as the
bailout condition.

Patch by Easwaran Raman, with some comment tweaks by me to try and
further clarify what is going on with this code.

http://reviews.llvm.org/D8267

llvm-svn: 238276
2015-05-27 02:49:05 +00:00

38 lines
1.0 KiB
LLVM

; RUN: opt < %s -inline -inline-threshold=35 -S | FileCheck %s
define i32 @bar(<4 x i32> %v, i32 %i) #0 {
entry:
%cmp = icmp sgt i32 %i, 4
br i1 %cmp, label %if.then, label %if.else
if.then: ; preds = %entry
%mul1 = mul nsw i32 %i, %i
br label %return
if.else: ; preds = %entry
%add1 = add nsw i32 %i, %i
%add2 = add nsw i32 %i, %i
%add3 = add nsw i32 %i, %i
%add4 = add nsw i32 %i, %i
%add5 = add nsw i32 %i, %i
%add6 = add nsw i32 %i, %i
%vecext = extractelement <4 x i32> %v, i32 0
%vecext7 = extractelement <4 x i32> %v, i32 1
%add7 = add nsw i32 %vecext, %vecext7
br label %return
return: ; preds = %if.else, %if.then
%retval.0 = phi i32 [ %mul1, %if.then ], [ %add7, %if.else ]
ret i32 %retval.0
}
define i32 @foo(<4 x i32> %v, i32 %a) #1 {
; CHECK-LABEL: @foo(
; CHECK-NOT: call i32 @bar
; CHECK: ret
entry:
%call = call i32 @bar(<4 x i32> %v, i32 %a)
ret i32 %call
}