[AMDGPU] Calculate getDivNumBits' AtLeast using bitwidth (llvm#121758)

Previously in shrinkDivRem64, it used fixed value 32 for AtLeast which
meant that <64bit divisions would be rejected from shrinking since logic
depended only on number of sign bits. I.e. 'idiv i48 %0, %1' would
return 24 for number of sign bits if %0,%1 both had 24 division bits,
and was rejected.

Author: choikwa

llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp

@@ -1523,7 +1523,8 @@ Value *AMDGPUCodeGenPrepareImpl::shrinkDivRem64(IRBuilder<> &Builder,
   bool IsDiv = Opc == Instruction::SDiv || Opc == Instruction::UDiv;
   bool IsSigned = Opc == Instruction::SDiv || Opc == Instruction::SRem;
 
-  int NumDivBits = getDivNumBits(I, Num, Den, 32, IsSigned);
+  unsigned BitWidth = Num->getType()->getScalarSizeInBits();
+  int NumDivBits = getDivNumBits(I, Num, Den, BitWidth - 32, IsSigned);
   if (NumDivBits == -1)
     return nullptr;
 

llvm/test/CodeGen/AMDGPU/sdiv64.ll

@@ -1065,100 +1065,37 @@ define amdgpu_kernel void @s_test_sdiv24_48(ptr addrspace(1) %out, i48 %x, i48 %
 ; GCN-NEXT:    s_endpgm
 ;
 ; GCN-IR-LABEL: s_test_sdiv24_48:
-; GCN-IR:       ; %bb.0: ; %_udiv-special-cases
-; GCN-IR-NEXT:    s_load_dwordx4 s[0:3], s[4:5], 0xb
-; GCN-IR-NEXT:    s_mov_b32 s15, 0
-; GCN-IR-NEXT:    s_waitcnt lgkmcnt(0)
-; GCN-IR-NEXT:    s_sext_i32_i16 s1, s1
-; GCN-IR-NEXT:    s_ashr_i64 s[0:1], s[0:1], 24
-; GCN-IR-NEXT:    s_sext_i32_i16 s3, s3
-; GCN-IR-NEXT:    s_lshl_b64 s[0:1], s[0:1], 16
-; GCN-IR-NEXT:    s_ashr_i64 s[2:3], s[2:3], 24
-; GCN-IR-NEXT:    s_ashr_i64 s[6:7], s[0:1], 16
-; GCN-IR-NEXT:    s_ashr_i32 s0, s1, 31
-; GCN-IR-NEXT:    s_lshl_b64 s[2:3], s[2:3], 16
-; GCN-IR-NEXT:    s_mov_b32 s1, s0
-; GCN-IR-NEXT:    s_ashr_i64 s[8:9], s[2:3], 16
-; GCN-IR-NEXT:    s_ashr_i32 s2, s3, 31
-; GCN-IR-NEXT:    s_xor_b64 s[6:7], s[6:7], s[0:1]
-; GCN-IR-NEXT:    s_mov_b32 s3, s2
-; GCN-IR-NEXT:    s_sub_u32 s12, s6, s0
-; GCN-IR-NEXT:    s_subb_u32 s13, s7, s0
-; GCN-IR-NEXT:    s_xor_b64 s[6:7], s[8:9], s[2:3]
-; GCN-IR-NEXT:    s_sub_u32 s6, s6, s2
-; GCN-IR-NEXT:    s_subb_u32 s7, s7, s2
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[8:9], s[6:7], 0
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[10:11], s[12:13], 0
-; GCN-IR-NEXT:    s_flbit_i32_b64 s14, s[6:7]
-; GCN-IR-NEXT:    s_or_b64 s[10:11], s[8:9], s[10:11]
-; GCN-IR-NEXT:    s_flbit_i32_b64 s20, s[12:13]
-; GCN-IR-NEXT:    s_sub_u32 s16, s14, s20
-; GCN-IR-NEXT:    s_subb_u32 s17, 0, 0
-; GCN-IR-NEXT:    v_cmp_gt_u64_e64 s[18:19], s[16:17], 63
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[22:23], s[16:17], 63
-; GCN-IR-NEXT:    s_or_b64 s[18:19], s[10:11], s[18:19]
-; GCN-IR-NEXT:    s_and_b64 s[10:11], s[18:19], exec
-; GCN-IR-NEXT:    s_cselect_b32 s11, 0, s13
-; GCN-IR-NEXT:    s_cselect_b32 s10, 0, s12
-; GCN-IR-NEXT:    s_or_b64 s[18:19], s[18:19], s[22:23]
-; GCN-IR-NEXT:    s_mov_b64 s[8:9], 0
-; GCN-IR-NEXT:    s_andn2_b64 vcc, exec, s[18:19]
-; GCN-IR-NEXT:    s_cbranch_vccz .LBB9_5
-; GCN-IR-NEXT:  ; %bb.1: ; %udiv-bb1
-; GCN-IR-NEXT:    s_add_u32 s18, s16, 1
-; GCN-IR-NEXT:    s_addc_u32 s19, s17, 0
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[10:11], s[18:19], 0
-; GCN-IR-NEXT:    s_sub_i32 s16, 63, s16
-; GCN-IR-NEXT:    s_andn2_b64 vcc, exec, s[10:11]
-; GCN-IR-NEXT:    s_lshl_b64 s[10:11], s[12:13], s16
-; GCN-IR-NEXT:    s_cbranch_vccz .LBB9_4
-; GCN-IR-NEXT:  ; %bb.2: ; %udiv-preheader
-; GCN-IR-NEXT:    s_lshr_b64 s[16:17], s[12:13], s18
-; GCN-IR-NEXT:    s_add_u32 s18, s6, -1
-; GCN-IR-NEXT:    s_addc_u32 s19, s7, -1
-; GCN-IR-NEXT:    s_not_b64 s[8:9], s[14:15]
-; GCN-IR-NEXT:    s_add_u32 s12, s8, s20
-; GCN-IR-NEXT:    s_addc_u32 s13, s9, 0
-; GCN-IR-NEXT:    s_mov_b64 s[14:15], 0
-; GCN-IR-NEXT:    s_mov_b32 s9, 0
-; GCN-IR-NEXT:  .LBB9_3: ; %udiv-do-while
-; GCN-IR-NEXT:    ; =>This Inner Loop Header: Depth=1
-; GCN-IR-NEXT:    s_lshl_b64 s[16:17], s[16:17], 1
-; GCN-IR-NEXT:    s_lshr_b32 s8, s11, 31
-; GCN-IR-NEXT:    s_lshl_b64 s[10:11], s[10:11], 1
-; GCN-IR-NEXT:    s_or_b64 s[16:17], s[16:17], s[8:9]
-; GCN-IR-NEXT:    s_or_b64 s[10:11], s[14:15], s[10:11]
-; GCN-IR-NEXT:    s_sub_u32 s8, s18, s16
-; GCN-IR-NEXT:    s_subb_u32 s8, s19, s17
-; GCN-IR-NEXT:    s_ashr_i32 s14, s8, 31
-; GCN-IR-NEXT:    s_mov_b32 s15, s14
-; GCN-IR-NEXT:    s_and_b32 s8, s14, 1
-; GCN-IR-NEXT:    s_and_b64 s[14:15], s[14:15], s[6:7]
-; GCN-IR-NEXT:    s_sub_u32 s16, s16, s14
-; GCN-IR-NEXT:    s_subb_u32 s17, s17, s15
-; GCN-IR-NEXT:    s_add_u32 s12, s12, 1
-; GCN-IR-NEXT:    s_addc_u32 s13, s13, 0
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[20:21], s[12:13], 0
-; GCN-IR-NEXT:    s_mov_b64 s[14:15], s[8:9]
-; GCN-IR-NEXT:    s_and_b64 vcc, exec, s[20:21]
-; GCN-IR-NEXT:    s_cbranch_vccz .LBB9_3
-; GCN-IR-NEXT:  .LBB9_4: ; %Flow4
-; GCN-IR-NEXT:    s_lshl_b64 s[6:7], s[10:11], 1
-; GCN-IR-NEXT:    s_or_b64 s[10:11], s[8:9], s[6:7]
-; GCN-IR-NEXT:  .LBB9_5: ; %udiv-end
-; GCN-IR-NEXT:    s_load_dwordx2 s[4:5], s[4:5], 0x9
-; GCN-IR-NEXT:    s_xor_b64 s[0:1], s[2:3], s[0:1]
-; GCN-IR-NEXT:    s_xor_b64 s[2:3], s[10:11], s[0:1]
-; GCN-IR-NEXT:    s_sub_u32 s0, s2, s0
-; GCN-IR-NEXT:    s_subb_u32 s1, s3, s1
+; GCN-IR:       ; %bb.0:
+; GCN-IR-NEXT:    s_load_dwordx4 s[0:3], s[4:5], 0x9
+; GCN-IR-NEXT:    s_load_dwordx2 s[8:9], s[4:5], 0xd
 ; GCN-IR-NEXT:    s_mov_b32 s7, 0xf000
 ; GCN-IR-NEXT:    s_mov_b32 s6, -1
-; GCN-IR-NEXT:    v_mov_b32_e32 v0, s1
 ; GCN-IR-NEXT:    s_waitcnt lgkmcnt(0)
-; GCN-IR-NEXT:    buffer_store_short v0, off, s[4:7], 0 offset:4
-; GCN-IR-NEXT:    s_waitcnt expcnt(0)
-; GCN-IR-NEXT:    v_mov_b32_e32 v0, s0
+; GCN-IR-NEXT:    s_mov_b32 s5, s1
+; GCN-IR-NEXT:    s_sext_i32_i16 s1, s9
+; GCN-IR-NEXT:    v_mov_b32_e32 v0, s8
+; GCN-IR-NEXT:    v_alignbit_b32 v0, s1, v0, 24
+; GCN-IR-NEXT:    v_cvt_f32_i32_e32 v1, v0
+; GCN-IR-NEXT:    s_mov_b32 s4, s0
+; GCN-IR-NEXT:    s_sext_i32_i16 s0, s3
+; GCN-IR-NEXT:    v_mov_b32_e32 v2, s2
+; GCN-IR-NEXT:    v_alignbit_b32 v2, s0, v2, 24
+; GCN-IR-NEXT:    v_cvt_f32_i32_e32 v3, v2
+; GCN-IR-NEXT:    v_rcp_iflag_f32_e32 v4, v1
+; GCN-IR-NEXT:    v_xor_b32_e32 v0, v2, v0
+; GCN-IR-NEXT:    v_ashrrev_i32_e32 v0, 30, v0
+; GCN-IR-NEXT:    v_or_b32_e32 v0, 1, v0
+; GCN-IR-NEXT:    v_mul_f32_e32 v2, v3, v4
+; GCN-IR-NEXT:    v_trunc_f32_e32 v2, v2
+; GCN-IR-NEXT:    v_mad_f32 v3, -v2, v1, v3
+; GCN-IR-NEXT:    v_cvt_i32_f32_e32 v2, v2
+; GCN-IR-NEXT:    v_cmp_ge_f32_e64 vcc, |v3|, |v1|
+; GCN-IR-NEXT:    v_cndmask_b32_e32 v0, 0, v0, vcc
+; GCN-IR-NEXT:    v_add_i32_e32 v0, vcc, v0, v2
+; GCN-IR-NEXT:    v_bfe_i32 v0, v0, 0, 24
+; GCN-IR-NEXT:    v_ashrrev_i32_e32 v1, 31, v0
 ; GCN-IR-NEXT:    buffer_store_dword v0, off, s[4:7], 0
+; GCN-IR-NEXT:    buffer_store_short v1, off, s[4:7], 0 offset:4
 ; GCN-IR-NEXT:    s_endpgm
   %1 = ashr i48 %x, 24
   %2 = ashr i48 %y, 24

llvm/test/CodeGen/AMDGPU/srem64.ll

@@ -1188,109 +1188,39 @@ define amdgpu_kernel void @s_test_srem24_48(ptr addrspace(1) %out, i48 %x, i48 %
 ; GCN-NEXT:    s_endpgm
 ;
 ; GCN-IR-LABEL: s_test_srem24_48:
-; GCN-IR:       ; %bb.0: ; %_udiv-special-cases
-; GCN-IR-NEXT:    s_load_dwordx4 s[0:3], s[4:5], 0xb
-; GCN-IR-NEXT:    s_mov_b32 s13, 0
+; GCN-IR:       ; %bb.0:
+; GCN-IR-NEXT:    s_load_dwordx4 s[0:3], s[4:5], 0x9
+; GCN-IR-NEXT:    s_load_dwordx2 s[4:5], s[4:5], 0xd
+; GCN-IR-NEXT:    s_mov_b32 s7, 0xf000
+; GCN-IR-NEXT:    s_mov_b32 s6, -1
 ; GCN-IR-NEXT:    s_waitcnt lgkmcnt(0)
-; GCN-IR-NEXT:    s_sext_i32_i16 s1, s1
 ; GCN-IR-NEXT:    s_sext_i32_i16 s3, s3
-; GCN-IR-NEXT:    s_ashr_i64 s[0:1], s[0:1], 24
-; GCN-IR-NEXT:    s_ashr_i64 s[2:3], s[2:3], 24
-; GCN-IR-NEXT:    s_lshl_b64 s[0:1], s[0:1], 16
-; GCN-IR-NEXT:    s_lshl_b64 s[6:7], s[2:3], 16
-; GCN-IR-NEXT:    s_ashr_i64 s[2:3], s[0:1], 16
-; GCN-IR-NEXT:    s_ashr_i32 s0, s1, 31
-; GCN-IR-NEXT:    s_mov_b32 s1, s0
-; GCN-IR-NEXT:    s_ashr_i64 s[8:9], s[6:7], 16
-; GCN-IR-NEXT:    s_xor_b64 s[2:3], s[2:3], s[0:1]
-; GCN-IR-NEXT:    s_sub_u32 s2, s2, s0
-; GCN-IR-NEXT:    s_subb_u32 s3, s3, s0
-; GCN-IR-NEXT:    s_ashr_i32 s10, s7, 31
-; GCN-IR-NEXT:    s_mov_b32 s11, s10
-; GCN-IR-NEXT:    s_xor_b64 s[6:7], s[8:9], s[10:11]
-; GCN-IR-NEXT:    s_sub_u32 s6, s6, s10
-; GCN-IR-NEXT:    s_subb_u32 s7, s7, s10
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[8:9], s[6:7], 0
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[10:11], s[2:3], 0
-; GCN-IR-NEXT:    s_flbit_i32_b64 s12, s[6:7]
-; GCN-IR-NEXT:    s_or_b64 s[10:11], s[8:9], s[10:11]
-; GCN-IR-NEXT:    s_flbit_i32_b64 s20, s[2:3]
-; GCN-IR-NEXT:    s_sub_u32 s14, s12, s20
-; GCN-IR-NEXT:    s_subb_u32 s15, 0, 0
-; GCN-IR-NEXT:    v_cmp_gt_u64_e64 s[16:17], s[14:15], 63
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[18:19], s[14:15], 63
-; GCN-IR-NEXT:    s_or_b64 s[16:17], s[10:11], s[16:17]
-; GCN-IR-NEXT:    s_and_b64 s[10:11], s[16:17], exec
-; GCN-IR-NEXT:    s_cselect_b32 s11, 0, s3
-; GCN-IR-NEXT:    s_cselect_b32 s10, 0, s2
-; GCN-IR-NEXT:    s_or_b64 s[16:17], s[16:17], s[18:19]
-; GCN-IR-NEXT:    s_mov_b64 s[8:9], 0
-; GCN-IR-NEXT:    s_andn2_b64 vcc, exec, s[16:17]
-; GCN-IR-NEXT:    s_cbranch_vccz .LBB9_5
-; GCN-IR-NEXT:  ; %bb.1: ; %udiv-bb1
-; GCN-IR-NEXT:    s_add_u32 s16, s14, 1
-; GCN-IR-NEXT:    s_addc_u32 s17, s15, 0
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[10:11], s[16:17], 0
-; GCN-IR-NEXT:    s_sub_i32 s14, 63, s14
-; GCN-IR-NEXT:    s_andn2_b64 vcc, exec, s[10:11]
-; GCN-IR-NEXT:    s_lshl_b64 s[10:11], s[2:3], s14
-; GCN-IR-NEXT:    s_cbranch_vccz .LBB9_4
-; GCN-IR-NEXT:  ; %bb.2: ; %udiv-preheader
-; GCN-IR-NEXT:    s_lshr_b64 s[14:15], s[2:3], s16
-; GCN-IR-NEXT:    s_add_u32 s18, s6, -1
-; GCN-IR-NEXT:    s_addc_u32 s19, s7, -1
-; GCN-IR-NEXT:    s_not_b64 s[8:9], s[12:13]
-; GCN-IR-NEXT:    s_add_u32 s12, s8, s20
-; GCN-IR-NEXT:    s_addc_u32 s13, s9, 0
-; GCN-IR-NEXT:    s_mov_b64 s[16:17], 0
-; GCN-IR-NEXT:    s_mov_b32 s9, 0
-; GCN-IR-NEXT:  .LBB9_3: ; %udiv-do-while
-; GCN-IR-NEXT:    ; =>This Inner Loop Header: Depth=1
-; GCN-IR-NEXT:    s_lshl_b64 s[14:15], s[14:15], 1
-; GCN-IR-NEXT:    s_lshr_b32 s8, s11, 31
-; GCN-IR-NEXT:    s_lshl_b64 s[10:11], s[10:11], 1
-; GCN-IR-NEXT:    s_or_b64 s[14:15], s[14:15], s[8:9]
-; GCN-IR-NEXT:    s_or_b64 s[10:11], s[16:17], s[10:11]
-; GCN-IR-NEXT:    s_sub_u32 s8, s18, s14
-; GCN-IR-NEXT:    s_subb_u32 s8, s19, s15
-; GCN-IR-NEXT:    s_ashr_i32 s16, s8, 31
-; GCN-IR-NEXT:    s_mov_b32 s17, s16
-; GCN-IR-NEXT:    s_and_b32 s8, s16, 1
-; GCN-IR-NEXT:    s_and_b64 s[16:17], s[16:17], s[6:7]
-; GCN-IR-NEXT:    s_sub_u32 s14, s14, s16
-; GCN-IR-NEXT:    s_subb_u32 s15, s15, s17
-; GCN-IR-NEXT:    s_add_u32 s12, s12, 1
-; GCN-IR-NEXT:    s_addc_u32 s13, s13, 0
-; GCN-IR-NEXT:    v_cmp_eq_u64_e64 s[20:21], s[12:13], 0
-; GCN-IR-NEXT:    s_mov_b64 s[16:17], s[8:9]
-; GCN-IR-NEXT:    s_and_b64 vcc, exec, s[20:21]
-; GCN-IR-NEXT:    s_cbranch_vccz .LBB9_3
-; GCN-IR-NEXT:  .LBB9_4: ; %Flow4
-; GCN-IR-NEXT:    s_lshl_b64 s[10:11], s[10:11], 1
-; GCN-IR-NEXT:    s_or_b64 s[10:11], s[8:9], s[10:11]
-; GCN-IR-NEXT:  .LBB9_5: ; %udiv-end
-; GCN-IR-NEXT:    v_mov_b32_e32 v0, s10
-; GCN-IR-NEXT:    v_mul_hi_u32 v0, s6, v0
-; GCN-IR-NEXT:    s_load_dwordx2 s[12:13], s[4:5], 0x9
-; GCN-IR-NEXT:    s_mul_i32 s4, s6, s11
-; GCN-IR-NEXT:    v_mov_b32_e32 v2, s3
-; GCN-IR-NEXT:    v_add_i32_e32 v0, vcc, s4, v0
-; GCN-IR-NEXT:    s_mul_i32 s4, s7, s10
-; GCN-IR-NEXT:    v_add_i32_e32 v0, vcc, s4, v0
-; GCN-IR-NEXT:    s_mul_i32 s4, s6, s10
-; GCN-IR-NEXT:    v_mov_b32_e32 v1, s4
-; GCN-IR-NEXT:    v_sub_i32_e32 v1, vcc, s2, v1
-; GCN-IR-NEXT:    v_subb_u32_e32 v0, vcc, v2, v0, vcc
-; GCN-IR-NEXT:    v_xor_b32_e32 v1, s0, v1
-; GCN-IR-NEXT:    v_xor_b32_e32 v0, s1, v0
-; GCN-IR-NEXT:    v_mov_b32_e32 v2, s1
-; GCN-IR-NEXT:    v_subrev_i32_e32 v1, vcc, s0, v1
-; GCN-IR-NEXT:    s_mov_b32 s15, 0xf000
-; GCN-IR-NEXT:    s_mov_b32 s14, -1
-; GCN-IR-NEXT:    v_subb_u32_e32 v0, vcc, v0, v2, vcc
-; GCN-IR-NEXT:    s_waitcnt lgkmcnt(0)
-; GCN-IR-NEXT:    buffer_store_short v0, off, s[12:15], 0 offset:4
-; GCN-IR-NEXT:    buffer_store_dword v1, off, s[12:15], 0
+; GCN-IR-NEXT:    s_sext_i32_i16 s5, s5
+; GCN-IR-NEXT:    v_mov_b32_e32 v0, s4
+; GCN-IR-NEXT:    v_alignbit_b32 v0, s5, v0, 24
+; GCN-IR-NEXT:    v_cvt_f32_i32_e32 v1, v0
+; GCN-IR-NEXT:    v_mov_b32_e32 v2, s2
+; GCN-IR-NEXT:    v_alignbit_b32 v2, s3, v2, 24
+; GCN-IR-NEXT:    v_cvt_f32_i32_e32 v3, v2
+; GCN-IR-NEXT:    v_rcp_iflag_f32_e32 v4, v1
+; GCN-IR-NEXT:    v_xor_b32_e32 v5, v2, v0
+; GCN-IR-NEXT:    v_ashrrev_i32_e32 v5, 30, v5
+; GCN-IR-NEXT:    v_or_b32_e32 v5, 1, v5
+; GCN-IR-NEXT:    v_mul_f32_e32 v4, v3, v4
+; GCN-IR-NEXT:    v_trunc_f32_e32 v4, v4
+; GCN-IR-NEXT:    v_mad_f32 v3, -v4, v1, v3
+; GCN-IR-NEXT:    v_cvt_i32_f32_e32 v4, v4
+; GCN-IR-NEXT:    v_cmp_ge_f32_e64 vcc, |v3|, |v1|
+; GCN-IR-NEXT:    v_cndmask_b32_e32 v1, 0, v5, vcc
+; GCN-IR-NEXT:    s_mov_b32 s4, s0
+; GCN-IR-NEXT:    v_add_i32_e32 v1, vcc, v1, v4
+; GCN-IR-NEXT:    v_mul_lo_u32 v0, v1, v0
+; GCN-IR-NEXT:    s_mov_b32 s5, s1
+; GCN-IR-NEXT:    v_subrev_i32_e32 v0, vcc, v0, v2
+; GCN-IR-NEXT:    v_bfe_i32 v0, v0, 0, 24
+; GCN-IR-NEXT:    v_ashrrev_i32_e32 v1, 31, v0
+; GCN-IR-NEXT:    buffer_store_dword v0, off, s[4:7], 0
+; GCN-IR-NEXT:    buffer_store_short v1, off, s[4:7], 0 offset:4
 ; GCN-IR-NEXT:    s_endpgm
   %1 = ashr i48 %x, 24
   %2 = ashr i48 %y, 24