347db3e18e
Summary: SystemZ shift instructions only use the last 6 bits of the shift amount. When the result of an AND operation is used as a shift amount, this means that we can use the NILL instruction (which operates on the last 16 bits) rather than NILF (which operates on the last 32 bits) for a 16-bit savings in instruction size. Reviewers: uweigand Subscribers: llvm-commits Author: colpell Committing on behalf of Elliot. Differential Revision: http://reviews.llvm.org/D21686 llvm-svn: 274066
36 lines
733 B
LLVM
36 lines
733 B
LLVM
; Test shortening of NILL to NILF when the result is used as a rotate amount.
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;
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; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
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; Test 32-bit rotate.
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define i32 @f1(i32 %val, i32 %amt) {
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; CHECK-LABEL: f1:
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; CHECK: nill %r3, 31
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; CHECK: rll %r2, %r2, 0(%r3)
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%mod = urem i32 %amt, 32
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%inv = sub i32 32, %mod
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%parta = shl i32 %val, %mod
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%partb = lshr i32 %val, %inv
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%rotl = or i32 %parta, %partb
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ret i32 %rotl
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}
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; Test 64-bit rotate.
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define i64 @f2(i64 %val, i64 %amt) {
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; CHECK-LABEL: f2:
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; CHECK: nill %r3, 63
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; CHECK: rllg %r2, %r2, 0(%r3)
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%mod = urem i64 %amt, 64
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%inv = sub i64 64, %mod
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%parta = shl i64 %val, %mod
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%partb = lshr i64 %val, %inv
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%rotl = or i64 %parta, %partb
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ret i64 %rotl
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}
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