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llvm-mirror/test/CodeGen/X86/widen_cast-1.ll
Andrew Trick e3e67d4a0a Enable MI Sched for x86.
This changes the SelectionDAG scheduling preference to source
order. Soon, the SelectionDAG scheduler can be bypassed saving
a nice chunk of compile time.

Performance differences that result from this change are often a
consequence of register coalescing. The register coalescer is far from
perfect. Bugs can be filed for deficiencies.

On x86 SandyBridge/Haswell, the source order schedule is often
preserved, particularly for small blocks.

Register pressure is generally improved over the SD scheduler's ILP
mode. However, we are still able to handle large blocks that require
latency hiding, unlike the SD scheduler's BURR mode. MI scheduler also
attempts to discover the critical path in single-block loops and
adjust heuristics accordingly.

The MI scheduler relies on the new machine model. This is currently
unimplemented for AVX, so we may not be generating the best code yet.

Unit tests are updated so they don't depend on SD scheduling heuristics.

llvm-svn: 192750
2013-10-15 23:33:07 +00:00

52 lines
1.7 KiB
LLVM

; RUN: llc -march=x86 -mcpu=generic -mattr=+sse4.2 < %s | FileCheck %s
; RUN: llc -march=x86 -mcpu=atom < %s | FileCheck -check-prefix=ATOM %s
; CHECK: movl
; CHECK: paddd
; CHECK: movlpd
; Scheduler causes produce a different instruction order
; ATOM: movl
; ATOM: paddd
; ATOM: movlpd
; bitcast a v4i16 to v2i32
define void @convert(<2 x i32>* %dst, <4 x i16>* %src) nounwind {
entry:
%dst.addr = alloca <2 x i32>* ; <<2 x i32>**> [#uses=2]
%src.addr = alloca <4 x i16>* ; <<4 x i16>**> [#uses=2]
%i = alloca i32, align 4 ; <i32*> [#uses=6]
store <2 x i32>* %dst, <2 x i32>** %dst.addr
store <4 x i16>* %src, <4 x i16>** %src.addr
store i32 0, i32* %i
br label %forcond
forcond: ; preds = %forinc, %entry
%tmp = load i32* %i ; <i32> [#uses=1]
%cmp = icmp slt i32 %tmp, 4 ; <i1> [#uses=1]
br i1 %cmp, label %forbody, label %afterfor
forbody: ; preds = %forcond
%tmp1 = load i32* %i ; <i32> [#uses=1]
%tmp2 = load <2 x i32>** %dst.addr ; <<2 x i32>*> [#uses=1]
%arrayidx = getelementptr <2 x i32>* %tmp2, i32 %tmp1 ; <<2 x i32>*> [#uses=1]
%tmp3 = load i32* %i ; <i32> [#uses=1]
%tmp4 = load <4 x i16>** %src.addr ; <<4 x i16>*> [#uses=1]
%arrayidx5 = getelementptr <4 x i16>* %tmp4, i32 %tmp3 ; <<4 x i16>*> [#uses=1]
%tmp6 = load <4 x i16>* %arrayidx5 ; <<4 x i16>> [#uses=1]
%add = add <4 x i16> %tmp6, < i16 1, i16 1, i16 1, i16 1 > ; <<4 x i16>> [#uses=1]
%conv = bitcast <4 x i16> %add to <2 x i32> ; <<2 x i32>> [#uses=1]
store <2 x i32> %conv, <2 x i32>* %arrayidx
br label %forinc
forinc: ; preds = %forbody
%tmp7 = load i32* %i ; <i32> [#uses=1]
%inc = add i32 %tmp7, 1 ; <i32> [#uses=1]
store i32 %inc, i32* %i
br label %forcond
afterfor: ; preds = %forcond
ret void
}