diff options
Diffstat (limited to 'lib/builtins/arm/udivsi3.S')
| -rw-r--r-- | lib/builtins/arm/udivsi3.S | 79 |
1 files changed, 38 insertions, 41 deletions
diff --git a/lib/builtins/arm/udivsi3.S b/lib/builtins/arm/udivsi3.S index 6dea27d40..9b1b035b3 100644 --- a/lib/builtins/arm/udivsi3.S +++ b/lib/builtins/arm/udivsi3.S @@ -1,16 +1,15 @@ -/*===-- udivsi3.S - 32-bit unsigned integer divide ------------------------===// - * - * The LLVM Compiler Infrastructure - * - * This file is dual licensed under the MIT and the University of Illinois Open - * Source Licenses. See LICENSE.TXT for details. - * - *===----------------------------------------------------------------------===// - * - * This file implements the __udivsi3 (32-bit unsigned integer divide) - * function for the ARM 32-bit architecture. - * - *===----------------------------------------------------------------------===*/ +//===-- udivsi3.S - 32-bit unsigned integer divide ------------------------===// +// +// 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 __udivsi3 (32-bit unsigned integer divide) +// function for the ARM 32-bit architecture. +// +//===----------------------------------------------------------------------===// #include "../assembly.h" @@ -40,7 +39,7 @@ LOCAL_LABEL(divby0): JMP(lr) # endif -#else /* ! __ARM_ARCH_EXT_IDIV__ */ +#else // ! __ARM_ARCH_EXT_IDIV__ cmp r1, #1 bcc LOCAL_LABEL(divby0) #if defined(USE_THUMB_1) @@ -63,26 +62,24 @@ LOCAL_LABEL(num_ge_denom): JMPc(lr, cc) #endif - /* - * 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. - */ + // 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. # if defined(__ARM_FEATURE_CLZ) clz ip, r0 clz r3, r1 - /* r0 >= r1 implies clz(r0) <= clz(r1), so ip <= r3. */ + // 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 @@ -94,7 +91,7 @@ LOCAL_LABEL(num_ge_denom): sub ip, ip, r3, lsl #3 mov r3, #0 bx ip -# else /* No CLZ Feature */ +# else // No CLZ Feature # if defined(USE_THUMB_2) # error THUMB mode requires CLZ or UDIV # endif @@ -160,7 +157,7 @@ LOCAL_LABEL(skip_2): subhs ip, ip, #(2 * BLOCK_SIZE) # endif - /* Last block, no need to update r2 or r3. */ + // Last block, no need to update r2 or r3. # if defined(USE_THUMB_1) lsrs r3, r2, #1 cmp r3, r1 @@ -180,12 +177,12 @@ LOCAL_LABEL(skip_1): JMP(ip) # endif -# endif /* __ARM_FEATURE_CLZ */ +# endif // __ARM_FEATURE_CLZ #define IMM # - /* due to the range limit of branch in Thumb1, we have to place the - block closer */ + // due to the range limit of branch in Thumb1, we have to place the + // block closer LOCAL_LABEL(divby0): movs r0, #0 # if defined(__ARM_EABI__) @@ -204,13 +201,13 @@ LOCAL_LABEL(divby0): blo LOCAL_LABEL(block_skip_##shift); \ subs r0, r0, r2; \ LOCAL_LABEL(block_skip_##shift) :; \ - adcs r3, r3 /* same as ((r3 << 1) | Carry). Carry is set if r0 >= r2. */ + adcs r3, r3 // same as ((r3 << 1) | Carry). Carry is set if r0 >= r2. - /* TODO: if current location counter is not not word aligned, we don't - need the .p2align and nop */ - /* Label div0block must be word-aligned. First align block 31 */ + // TODO: if current location counter is not not word aligned, we don't + // need the .p2align and nop + // Label div0block must be word-aligned. First align block 31 .p2align 2 - nop /* Padding to align div0block as 31 blocks = 310 bytes */ + nop // Padding to align div0block as 31 blocks = 310 bytes #else #define block(shift) \ @@ -256,7 +253,7 @@ LOCAL_LABEL(div0block): mov r0, r3 JMP(lr) -#endif /* __ARM_ARCH_EXT_IDIV__ */ +#endif // __ARM_ARCH_EXT_IDIV__ END_COMPILERRT_FUNCTION(__udivsi3) |