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llvm-mirror/test/Transforms/InstCombine/2009-04-07-MulPromoteToI96.ll
Chris Lattner 7d75f78b92 Instcombine should not promote whole computation trees to "strange"
integer types, unless they are already strange.  This prevents it from
turning the code produced by SROA into crazy libcalls and stuff that 
the code generator can't handle.  In the attached example, the result
was an i96 multiply that caused the x86 backend to assert.

Note that if TargetData had an idea of what the legal types are for
a target that this could be used to stop instcombine from introducing
i64 muls, as Scott wanted.

llvm-svn: 68598
2009-04-08 05:41:03 +00:00

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LLVM

; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {mul i64}
; rdar://6762288
; Instcombine should not promote the mul to i96 because it is definitely
; not a legal type for the target, and we don't want a libcall.
define i96 @test(i96 %a.4, i96 %b.2) {
%tmp1086 = trunc i96 %a.4 to i64 ; <i64> [#uses=1]
%tmp836 = trunc i96 %b.2 to i64 ; <i64> [#uses=1]
%mul185 = mul i64 %tmp1086, %tmp836 ; <i64> [#uses=1]
%tmp544 = zext i64 %mul185 to i96 ; <i96> [#uses=1]
ret i96 %tmp544
}