34 lines
1.1 KiB
LLVM
34 lines
1.1 KiB
LLVM
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; RUN: llc < %s -mtriple=thumbv7-apple-ios -mcpu=cortex-a8 | FileCheck %s
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; ARM has a peephole optimization which looks for a def / use pair. The def
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; produces a 32-bit immediate which is consumed by the use. It tries to
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; fold the immediate by breaking it into two parts and fold them into the
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; immmediate fields of two uses. e.g
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; movw r2, #40885
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; movt r3, #46540
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; add r0, r0, r3
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; =>
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; add.w r0, r0, #3019898880
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; add.w r0, r0, #30146560
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;
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; However, this transformation is incorrect if the user produces a flag. e.g.
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; movw r2, #40885
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; movt r3, #46540
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; adds r0, r0, r3
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; =>
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; add.w r0, r0, #3019898880
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; adds.w r0, r0, #30146560
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; Note the adds.w may not set the carry flag even if the original sequence
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; would.
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;
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; rdar://11116189
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define i64 @t(i64 %aInput) nounwind {
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; CHECK: t:
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; CHECK: movs [[REG:(r[0-9]+)]], #0
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; CHECK: movt [[REG]], #46540
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; CHECK: adds r{{[0-9]+}}, r{{[0-9]+}}, [[REG]]
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%1 = mul i64 %aInput, 1000000
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%2 = add i64 %1, -7952618389194932224
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ret i64 %2
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}
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