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Stack trace: use popcount function instead of inline loop

This commit is contained in:
Adam Higerd 2020-07-27 22:06:44 -05:00
parent fec10dac32
commit 1a9ead1e25
1 changed files with 3 additions and 8 deletions
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11
src/arm/debugger/debugger.c
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@ -12,6 +12,7 @@
#include <mgba/internal/arm/debugger/memory-debugger.h>
#include <mgba/internal/debugger/parser.h>
#include <mgba/internal/debugger/stack-trace.h>
#include <mgba-util/math.h>
#include <stdint.h>
DEFINE_VECTOR(ARMDebugBreakpointList, struct ARMDebugBreakpoint);
@ -63,14 +64,8 @@ static bool ARMDebuggerUpdateStackTraceInternal(struct mDebuggerPlatform* d, uin
// need ANOTHER stack frame, so only skip if it's not.
} else if (info.operandFormat & ARM_OPERAND_MEMORY_1) {
// This is most likely ldmia ..., {..., pc}, which is a function return.
// To find which stack slot holds the return address, count number of set bits.
// (gcc/clang will convert the loop to intrinsics if available)
int regCount = 0;
uint32_t reglist = info.op1.immediate;
while (reglist != 0) {
reglist &= reglist - 1;
regCount++;
}
// To find which stack slot holds the return address, count the number of set bits.
int regCount = popcount32(info.op1.immediate);
uint32_t baseAddress = cpu->gprs[info.memory.baseReg] + ((regCount - 1) << 2);
destAddress = cpu->memory.load32(cpu, baseAddress, NULL);
} else if (info.operandFormat & ARM_OPERAND_IMMEDIATE_1) {