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David Green e547a3cc78 [ARM] Optimise ASRL/LSRL to smaller shifts using demand bits.
The ASRL/LSRL long shifts are generated from 64bit shifts. Once we have
them, it might turn out that enough of the 64bit result was not required
that we can use a smaller shift to perform the same result. As the
smaller shift can in general be folded in more way, such as into add
instructions in one of the test cases here, we can use the demand bit
analysis to prefer the smaller shifts where we can.

Differential Revision: https://reviews.llvm.org/D75371
2020-03-13 10:09:03 +00:00

54 lines
1.8 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc --verify-machineinstrs -mtriple=thumbv8.1m.main-none-eabi -mattr=+mve %s -o - | FileCheck %s -check-prefix=CHECK --check-prefix=CHECK-MVE
; RUN: llc --verify-machineinstrs -mtriple=thumbv8.1m.main-none-eabi -mattr=+dsp %s -o - | FileCheck %s -check-prefix=CHECK --check-prefix=CHECK-NOMVE
define void @test1(i32* %p0, i32 *%p1, i32 *%p2, i32 *%pDst) {
; CHECK-LABEL: test1:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: ldr r1, [r1]
; CHECK-NEXT: ldr r2, [r2]
; CHECK-NEXT: ldr r0, [r0]
; CHECK-NEXT: smmul r1, r2, r1
; CHECK-NEXT: add.w r0, r0, r1, lsl #1
; CHECK-NEXT: str r0, [r3]
; CHECK-NEXT: bx lr
entry:
%l3 = load i32, i32* %p0, align 4
%l4 = load i32, i32* %p1, align 4
%conv5.us = sext i32 %l4 to i64
%l5 = load i32, i32* %p2, align 4
%conv6.us = sext i32 %l5 to i64
%mul.us = mul nsw i64 %conv6.us, %conv5.us
%l6 = lshr i64 %mul.us, 31
%l7 = trunc i64 %l6 to i32
%shl.us = and i32 %l7, -2
%add.us = add nsw i32 %shl.us, %l3
store i32 %add.us, i32* %pDst, align 4
ret void
}
define void @test2(i32* %p0, i32 *%p1, i32 *%p2, i32 *%pDst) {
; CHECK-LABEL: test2:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: ldr r1, [r1]
; CHECK-NEXT: ldr r2, [r2]
; CHECK-NEXT: ldr r0, [r0]
; CHECK-NEXT: smmul r1, r2, r1
; CHECK-NEXT: add.w r0, r0, r1, lsl #1
; CHECK-NEXT: str r0, [r3]
; CHECK-NEXT: bx lr
entry:
%l3 = load i32, i32* %p0, align 4
%l4 = load i32, i32* %p1, align 4
%conv5.us = sext i32 %l4 to i64
%l5 = load i32, i32* %p2, align 4
%conv6.us = sext i32 %l5 to i64
%mul.us = mul nsw i64 %conv6.us, %conv5.us
%l6 = lshr i64 %mul.us, 32
%shl74.us = shl nuw nsw i64 %l6, 1
%shl.us = trunc i64 %shl74.us to i32
%add.us = add nsw i32 %l3, %shl.us
store i32 %add.us, i32* %pDst, align 4
ret void
}