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In function DAGCombiner::visitSIGN_EXTEND_INREG, sext can be combined with extload even if sextload is not supported by target, then if sext is the only user of extload, there is no big difference, no harm no benefit. if extload has more than one user, the combined sextload may block extload from combining with other zext, causes extra zext instructions generated. As demonstrated by the attached test case. This patch add the constraint that when sextload is not supported by target, sext can only be combined with extload if it is the only user of extload. Differential Revision: https://reviews.llvm.org/D39108 llvm-svn: 316802
27 lines
576 B
LLVM
27 lines
576 B
LLVM
; RUN: llc --mtriple=powerpc64le-linux-gnu < %s | FileCheck %s
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; It tests in function DAGCombiner::visitSIGN_EXTEND_INREG
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; signext will not be combined with extload, and causes extra zext.
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declare void @g(i32 signext)
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define void @foo(i8* %p) {
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entry:
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br label %while.body
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while.body:
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%0 = load i8, i8* %p, align 1
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%conv = zext i8 %0 to i32
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%cmp = icmp sgt i8 %0, 0
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br i1 %cmp, label %if.then, label %while.body
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; CHECK: lbz
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; CHECK: extsb.
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; CHECK-NOT: rlwinm
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; CHECK: ble
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if.then:
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tail call void @g(i32 signext %conv)
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br label %while.body
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}
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