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llvm-mirror/test/Transforms/InstCombine/2008-01-21-MulTrunc.ll
Chris Lattner c6bb31e5ea make instcombine only rewrite a chain of computation
(eliminating some extends) if the new type of the
computation is legal or if both the source and dest
are illegal.  This prevents instcombine from changing big
chains of computation into i64 on 32-bit targets for 
example.

llvm-svn: 86398
2009-11-07 19:11:46 +00:00

18 lines
747 B
LLVM

; RUN: opt < %s -instcombine -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
define i16 @test1(i16 %a) {
%tmp = zext i16 %a to i32 ; <i32> [#uses=2]
%tmp21 = lshr i32 %tmp, 8 ; <i32> [#uses=1]
; CHECK: %tmp21 = lshr i16 %a, 8
%tmp5 = mul i32 %tmp, 5 ; <i32> [#uses=1]
; CHECK: %tmp5 = mul i16 %a, 5
%tmp.upgrd.32 = or i32 %tmp21, %tmp5 ; <i32> [#uses=1]
; CHECK: %tmp.upgrd.32 = or i16 %tmp21, %tmp5
%tmp.upgrd.3 = trunc i32 %tmp.upgrd.32 to i16 ; <i16> [#uses=1]
ret i16 %tmp.upgrd.3
; CHECK: ret i16 %tmp.upgrd.32
}