1; RUN: llc -mtriple=arm-eabi %s -o - | FileCheck %s 2; RUN: llc -mtriple=armv6m-eabi %s -o - | FileCheck %s --check-prefix=EXPAND 3 4define i64 @test_shl(i64 %val, i64 %amt) { 5; CHECK-LABEL: test_shl: 6; EXPAND-LABEL: test_shl: 7 ; First calculate the hi part when the shift amount is small enough that it 8 ; contains components from both halves. It'll be returned in r1 so that's a 9 ; reasonable place for it to end up. 10; CHECK: rsb [[REVERSE_SHIFT:.*]], r2, #32 11; CHECK: lsr [[TMP:.*]], r0, [[REVERSE_SHIFT]] 12; CHECK: orr r1, [[TMP]], r1, lsl r2 13 14 ; Check whether the shift was in fact small (< 32 bits). 15; CHECK: sub [[EXTRA_SHIFT:.*]], r2, #32 16; CHECK: cmp [[EXTRA_SHIFT]], #0 17 18 ; If not, the high part of the answer is just the low part shifted by the 19 ; excess. 20; CHECK: lslge r1, r0, [[EXTRA_SHIFT]] 21 22 ; The low part is either a direct shift (1st inst) or 0. We can reuse the same 23 ; NZCV. 24; CHECK: lsl r0, r0, r2 25; CHECK: movge r0, #0 26 27; EXPAND: push {[[REG:r[0-9]+]], lr} 28; EXPAND-NEXT: bl __aeabi_llsl 29; EXPAND-NEXT: pop {[[REG]], pc} 30 %res = shl i64 %val, %amt 31 ret i64 %res 32} 33 34; Explanation for lshr is pretty much the reverse of shl. 35define i64 @test_lshr(i64 %val, i64 %amt) { 36; CHECK-LABEL: test_lshr: 37; EXPAND-LABEL: test_lshr: 38; CHECK: rsb [[REVERSE_SHIFT:.*]], r2, #32 39; CHECK: lsr r0, r0, r2 40; CHECK: orr r0, r0, r1, lsl [[REVERSE_SHIFT]] 41; CHECK: sub [[EXTRA_SHIFT:.*]], r2, #32 42; CHECK: cmp [[EXTRA_SHIFT]], #0 43; CHECK: lsrge r0, r1, [[EXTRA_SHIFT]] 44; CHECK: lsr r1, r1, r2 45; CHECK: movge r1, #0 46 47; EXPAND: push {[[REG:r[0-9]+]], lr} 48; EXPAND-NEXT: bl __aeabi_llsr 49; EXPAND-NEXT: pop {[[REG]], pc} 50 %res = lshr i64 %val, %amt 51 ret i64 %res 52} 53 54; One minor difference for ashr: the high bits must be "hi >> 31" if the shift 55; amount is large to get the right sign bit. 56define i64 @test_ashr(i64 %val, i64 %amt) { 57; CHECK-LABEL: test_ashr: 58; EXPAND-LABEL: test_ashr: 59; CHECK: sub [[EXTRA_SHIFT:.*]], r2, #32 60; CHECK: asr [[HI_TMP:.*]], r1, r2 61; CHECK: lsr r0, r0, r2 62; CHECK: rsb [[REVERSE_SHIFT:.*]], r2, #32 63; CHECK: cmp [[EXTRA_SHIFT]], #0 64; CHECK: orr r0, r0, r1, lsl [[REVERSE_SHIFT]] 65; CHECK: asrge [[HI_TMP]], r1, #31 66; CHECK: asrge r0, r1, [[EXTRA_SHIFT]] 67; CHECK: mov r1, [[HI_TMP]] 68 69; EXPAND: push {[[REG:r[0-9]+]], lr} 70; EXPAND-NEXT: bl __aeabi_lasr 71; EXPAND-NEXT: pop {[[REG]], pc} 72 %res = ashr i64 %val, %amt 73 ret i64 %res 74} 75