; RUN: llc -mtriple=arm-eabi %s -o - | FileCheck %s define i64 @test_shl(i64 %val, i64 %amt) { ; CHECK-LABEL: test_shl: ; First calculate the hi part when the shift amount is small enough that it ; contains components from both halves. It'll be returned in r1 so that's a ; reasonable place for it to end up. ; CHECK: rsb [[REVERSE_SHIFT:.*]], r2, #32 ; CHECK: lsr [[TMP:.*]], r0, [[REVERSE_SHIFT]] ; CHECK: orr r1, [[TMP]], r1, lsl r2 ; Check whether the shift was in fact small (< 32 bits). ; CHECK: sub [[EXTRA_SHIFT:.*]], r2, #32 ; CHECK: cmp [[EXTRA_SHIFT]], #0 ; If not, the high part of the answer is just the low part shifted by the ; excess. ; CHECK: lslge r1, r0, [[EXTRA_SHIFT]] ; The low part is either a direct shift (1st inst) or 0. We can reuse the same ; NZCV. ; CHECK: lsl r0, r0, r2 ; CHECK: movge r0, #0 %res = shl i64 %val, %amt ret i64 %res } ; Explanation for lshr is pretty much the reverse of shl. define i64 @test_lshr(i64 %val, i64 %amt) { ; CHECK-LABEL: test_lshr: ; CHECK: rsb [[REVERSE_SHIFT:.*]], r2, #32 ; CHECK: lsr r0, r0, r2 ; CHECK: orr r0, r0, r1, lsl [[REVERSE_SHIFT]] ; CHECK: sub [[EXTRA_SHIFT:.*]], r2, #32 ; CHECK: cmp [[EXTRA_SHIFT]], #0 ; CHECK: lsrge r0, r1, [[EXTRA_SHIFT]] ; CHECK: lsr r1, r1, r2 ; CHECK: movge r1, #0 %res = lshr i64 %val, %amt ret i64 %res } ; One minor difference for ashr: the high bits must be "hi >> 31" if the shift ; amount is large to get the right sign bit. define i64 @test_ashr(i64 %val, i64 %amt) { ; CHECK-LABEL: test_ashr: ; CHECK: sub [[EXTRA_SHIFT:.*]], r2, #32 ; CHECK: asr [[HI_TMP:.*]], r1, r2 ; CHECK: lsr r0, r0, r2 ; CHECK: rsb [[REVERSE_SHIFT:.*]], r2, #32 ; CHECK: cmp [[EXTRA_SHIFT]], #0 ; CHECK: orr r0, r0, r1, lsl [[REVERSE_SHIFT]] ; CHECK: asrge [[HI_TMP]], r1, #31 ; CHECK: asrge r0, r1, [[EXTRA_SHIFT]] ; CHECK: mov r1, [[HI_TMP]] %res = ashr i64 %val, %amt ret i64 %res }