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Diffstat (limited to 'contrib/llvm-project/compiler-rt/lib/builtins/arm/udivmodsi4.S')
| -rw-r--r-- | contrib/llvm-project/compiler-rt/lib/builtins/arm/udivmodsi4.S | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/contrib/llvm-project/compiler-rt/lib/builtins/arm/udivmodsi4.S b/contrib/llvm-project/compiler-rt/lib/builtins/arm/udivmodsi4.S new file mode 100644 index 000000000000..0f40575fe99e --- /dev/null +++ b/contrib/llvm-project/compiler-rt/lib/builtins/arm/udivmodsi4.S @@ -0,0 +1,178 @@ +//===-- udivmodsi4.S - 32-bit unsigned integer divide and modulus ---------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements the __udivmodsi4 (32-bit unsigned integer divide and +// modulus) function for the ARM 32-bit architecture. +// +//===----------------------------------------------------------------------===// + +#include "../assembly.h" + + .syntax unified + .text + DEFINE_CODE_STATE + +@ unsigned int __udivmodsi4(unsigned int divident, unsigned int divisor, +@ unsigned int *remainder) +@ Calculate the quotient and remainder of the (unsigned) division. The return +@ value is the quotient, the remainder is placed in the variable. + + .p2align 2 +DEFINE_COMPILERRT_FUNCTION(__udivmodsi4) +#if __ARM_ARCH_EXT_IDIV__ + tst r1, r1 + beq LOCAL_LABEL(divby0) + mov r3, r0 + udiv r0, r3, r1 + mls r1, r0, r1, r3 + str r1, [r2] + bx lr +#else + cmp r1, #1 + bcc LOCAL_LABEL(divby0) + beq LOCAL_LABEL(divby1) + cmp r0, r1 + bcc LOCAL_LABEL(quotient0) + + // Implement division using binary long division algorithm. + // + // r0 is the numerator, r1 the denominator. + // + // The code before JMP computes the correct shift I, so that + // r0 and (r1 << I) have the highest bit set in the same position. + // At the time of JMP, ip := .Ldiv0block - 12 * I. + // This depends on the fixed instruction size of block. + // For ARM mode, this is 12 Bytes, for THUMB mode 14 Bytes. + // + // block(shift) implements the test-and-update-quotient core. + // It assumes (r0 << shift) can be computed without overflow and + // that (r0 << shift) < 2 * r1. The quotient is stored in r3. + +# ifdef __ARM_FEATURE_CLZ + clz ip, r0 + clz r3, r1 + // r0 >= r1 implies clz(r0) <= clz(r1), so ip <= r3. + sub r3, r3, ip +# if defined(USE_THUMB_2) + adr ip, LOCAL_LABEL(div0block) + 1 + sub ip, ip, r3, lsl #1 +# else + adr ip, LOCAL_LABEL(div0block) +# endif + sub ip, ip, r3, lsl #2 + sub ip, ip, r3, lsl #3 + mov r3, #0 + bx ip +# else +# if defined(USE_THUMB_2) +# error THUMB mode requires CLZ or UDIV +# endif + str r4, [sp, #-8]! + + mov r4, r0 + adr ip, LOCAL_LABEL(div0block) + + lsr r3, r4, #16 + cmp r3, r1 + movhs r4, r3 + subhs ip, ip, #(16 * 12) + + lsr r3, r4, #8 + cmp r3, r1 + movhs r4, r3 + subhs ip, ip, #(8 * 12) + + lsr r3, r4, #4 + cmp r3, r1 + movhs r4, r3 + subhs ip, #(4 * 12) + + lsr r3, r4, #2 + cmp r3, r1 + movhs r4, r3 + subhs ip, ip, #(2 * 12) + + // Last block, no need to update r3 or r4. + cmp r1, r4, lsr #1 + subls ip, ip, #(1 * 12) + + ldr r4, [sp], #8 // restore r4, we are done with it. + mov r3, #0 + + JMP(ip) +# endif + +#define IMM # + +#define block(shift) \ + cmp r0, r1, lsl IMM shift; \ + ITT(hs); \ + WIDE(addhs) r3, r3, IMM (1 << shift); \ + WIDE(subhs) r0, r0, r1, lsl IMM shift + + block(31) + block(30) + block(29) + block(28) + block(27) + block(26) + block(25) + block(24) + block(23) + block(22) + block(21) + block(20) + block(19) + block(18) + block(17) + block(16) + block(15) + block(14) + block(13) + block(12) + block(11) + block(10) + block(9) + block(8) + block(7) + block(6) + block(5) + block(4) + block(3) + block(2) + block(1) +LOCAL_LABEL(div0block): + block(0) + + str r0, [r2] + mov r0, r3 + JMP(lr) + +LOCAL_LABEL(quotient0): + str r0, [r2] + mov r0, #0 + JMP(lr) + +LOCAL_LABEL(divby1): + mov r3, #0 + str r3, [r2] + JMP(lr) +#endif // __ARM_ARCH_EXT_IDIV__ + +LOCAL_LABEL(divby0): + mov r0, #0 +#ifdef __ARM_EABI__ + b __aeabi_idiv0 +#else + JMP(lr) +#endif + +END_COMPILERRT_FUNCTION(__udivmodsi4) + +NO_EXEC_STACK_DIRECTIVE + |