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llvm-mirror/test/CodeGen/AArch64/shift-by-signext.ll
Sjoerd Meijer ff9f01c06e [AArch64] Peephole optimization: merge AND and TST instructions
In some cases Clang does not perform merging of instructions AND and TST (aka
ANDS xzr).

Example:

  tst x2, x1
  and x3, x2, x1

to:

  ands x3, x2, x1

This patch add such merging during instruction selection: when AND is replaced
with ANDS instruction in LowerSELECT_CC, all users of AND also should be
changed for using this ANDS instruction

Short discussion on mailing list:
http://llvm.1065342.n5.nabble.com/llvm-dev-ARM-Peephole-optimization-instructions-tst-add-tp133109.html

Patch by Pavel Kosov.

Differential Revision: https://reviews.llvm.org/D71701
2020-02-27 09:23:47 +00:00

121 lines
3.7 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=aarch64-unknown-linux-gnu < %s | FileCheck %s
; If we have a shift by sign-extended value, we can replace sign-extension
; with zero-extension.
define i32 @t0_shl(i32 %x, i8 %shamt) nounwind {
; CHECK-LABEL: t0_shl:
; CHECK: // %bb.0:
; CHECK-NEXT: sxtb w8, w1
; CHECK-NEXT: lsl w0, w0, w8
; CHECK-NEXT: ret
%shamt_wide = sext i8 %shamt to i32
%r = shl i32 %x, %shamt_wide
ret i32 %r
}
define i32 @t1_lshr(i32 %x, i8 %shamt) nounwind {
; CHECK-LABEL: t1_lshr:
; CHECK: // %bb.0:
; CHECK-NEXT: sxtb w8, w1
; CHECK-NEXT: lsr w0, w0, w8
; CHECK-NEXT: ret
%shamt_wide = sext i8 %shamt to i32
%r = lshr i32 %x, %shamt_wide
ret i32 %r
}
define i32 @t2_ashr(i32 %x, i8 %shamt) nounwind {
; CHECK-LABEL: t2_ashr:
; CHECK: // %bb.0:
; CHECK-NEXT: sxtb w8, w1
; CHECK-NEXT: asr w0, w0, w8
; CHECK-NEXT: ret
%shamt_wide = sext i8 %shamt to i32
%r = ashr i32 %x, %shamt_wide
ret i32 %r
}
define <4 x i32> @t3_vec_shl(<4 x i32> %x, <4 x i8> %shamt) nounwind {
; CHECK-LABEL: t3_vec_shl:
; CHECK: // %bb.0:
; CHECK-NEXT: ushll v1.4s, v1.4h, #0
; CHECK-NEXT: shl v1.4s, v1.4s, #24
; CHECK-NEXT: sshr v1.4s, v1.4s, #24
; CHECK-NEXT: ushl v0.4s, v0.4s, v1.4s
; CHECK-NEXT: ret
%shamt_wide = sext <4 x i8> %shamt to <4 x i32>
%r = shl <4 x i32> %x, %shamt_wide
ret <4 x i32> %r
}
define <4 x i32> @t4_vec_lshr(<4 x i32> %x, <4 x i8> %shamt) nounwind {
; CHECK-LABEL: t4_vec_lshr:
; CHECK: // %bb.0:
; CHECK-NEXT: ushll v1.4s, v1.4h, #0
; CHECK-NEXT: shl v1.4s, v1.4s, #24
; CHECK-NEXT: sshr v1.4s, v1.4s, #24
; CHECK-NEXT: neg v1.4s, v1.4s
; CHECK-NEXT: ushl v0.4s, v0.4s, v1.4s
; CHECK-NEXT: ret
%shamt_wide = sext <4 x i8> %shamt to <4 x i32>
%r = lshr <4 x i32> %x, %shamt_wide
ret <4 x i32> %r
}
define <4 x i32> @t5_vec_ashr(<4 x i32> %x, <4 x i8> %shamt) nounwind {
; CHECK-LABEL: t5_vec_ashr:
; CHECK: // %bb.0:
; CHECK-NEXT: ushll v1.4s, v1.4h, #0
; CHECK-NEXT: shl v1.4s, v1.4s, #24
; CHECK-NEXT: sshr v1.4s, v1.4s, #24
; CHECK-NEXT: neg v1.4s, v1.4s
; CHECK-NEXT: sshl v0.4s, v0.4s, v1.4s
; CHECK-NEXT: ret
%shamt_wide = sext <4 x i8> %shamt to <4 x i32>
%r = ashr <4 x i32> %x, %shamt_wide
ret <4 x i32> %r
}
; This is not valid for funnel shifts
declare i32 @llvm.fshl.i32(i32 %a, i32 %b, i32 %c)
declare i32 @llvm.fshr.i32(i32 %a, i32 %b, i32 %c)
define i32 @n6_fshl(i32 %x, i32 %y, i8 %shamt) nounwind {
; CHECK-LABEL: n6_fshl:
; CHECK: // %bb.0:
; CHECK-NEXT: ands w9, w2, #0x1f
; CHECK-NEXT: neg w9, w9
; CHECK-NEXT: lsl w8, w0, w2
; CHECK-NEXT: lsr w9, w1, w9
; CHECK-NEXT: orr w8, w8, w9
; CHECK-NEXT: csel w0, w0, w8, eq
; CHECK-NEXT: ret
%shamt_wide = sext i8 %shamt to i32
%r = call i32 @llvm.fshl.i32(i32 %x, i32 %y, i32 %shamt_wide)
ret i32 %r
}
define i32 @n7_fshr(i32 %x, i32 %y, i8 %shamt) nounwind {
; CHECK-LABEL: n7_fshr:
; CHECK: // %bb.0:
; CHECK-NEXT: ands w9, w2, #0x1f
; CHECK-NEXT: neg w9, w9
; CHECK-NEXT: lsr w8, w1, w2
; CHECK-NEXT: lsl w9, w0, w9
; CHECK-NEXT: orr w8, w9, w8
; CHECK-NEXT: csel w0, w1, w8, eq
; CHECK-NEXT: ret
%shamt_wide = sext i8 %shamt to i32
%r = call i32 @llvm.fshr.i32(i32 %x, i32 %y, i32 %shamt_wide)
ret i32 %r
}
define i32 @n8_extrause(i32 %x, i8 %shamt, i32* %shamt_wide_store) nounwind {
; CHECK-LABEL: n8_extrause:
; CHECK: // %bb.0:
; CHECK-NEXT: sxtb w8, w1
; CHECK-NEXT: lsl w0, w0, w8
; CHECK-NEXT: str w8, [x2]
; CHECK-NEXT: ret
%shamt_wide = sext i8 %shamt to i32
store i32 %shamt_wide, i32* %shamt_wide_store, align 4
%r = shl i32 %x, %shamt_wide
ret i32 %r
}