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Shader JIT: Fix off-by-one error when compiling JMPs

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There was a mistake in the JMP code which meant that one instruction at
the destination would be skipped when the jump was taken. This commit
also changes the meaning of the culprit parameter to make it less
confusing and avoid similar mistakes in the future.
This commit is contained in:
Yuri Kunde Schlesner 2016-01-24 02:10:56 -08:00
parent 0b6cc0592d
commit c1071c1ff7
2 changed files with 6 additions and 6 deletions
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10
src/video_core/shader/shader_jit_x64.cpp
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@ -653,7 +653,7 @@ void JitCompiler::Compile_IF(Instruction instr) {
FixupBranch b = J_CC(CC_Z, true);
// Compile the code that corresponds to the condition evaluating as true
Compile_Block(instr.flow_control.dest_offset - 1);
Compile_Block(instr.flow_control.dest_offset);
// If there isn't an "ELSE" condition, we are done here
if (instr.flow_control.num_instructions == 0) {
@ -667,7 +667,7 @@ void JitCompiler::Compile_IF(Instruction instr) {
// This code corresponds to the "ELSE" condition
// Comple the code that corresponds to the condition evaluating as false
Compile_Block(instr.flow_control.dest_offset + instr.flow_control.num_instructions - 1);
Compile_Block(instr.flow_control.dest_offset + instr.flow_control.num_instructions);
SetJumpTarget(b2);
}
@ -691,7 +691,7 @@ void JitCompiler::Compile_LOOP(Instruction instr) {
auto loop_start = GetCodePtr();
Compile_Block(instr.flow_control.dest_offset);
Compile_Block(instr.flow_control.dest_offset + 1);
ADD(32, R(LOOPCOUNT_REG), R(LOOPINC)); // Increment LOOPCOUNT_REG by Z-component
SUB(32, R(LOOPCOUNT), Imm8(1)); // Increment loop count by 1
@ -717,12 +717,12 @@ void JitCompiler::Compile_JMP(Instruction instr) {
SetJumpTarget(b);
}
void JitCompiler::Compile_Block(unsigned stop) {
void JitCompiler::Compile_Block(unsigned end) {
// Save current offset pointer
unsigned* prev_offset_ptr = offset_ptr;
unsigned offset = *prev_offset_ptr;
while (offset <= stop)
while (offset < end)
Compile_NextInstr(&offset);
// Restore current offset pointer

2
src/video_core/shader/shader_jit_x64.h
View file

@ -61,7 +61,7 @@ public:
void Compile_MAD(Instruction instr);
private:
void Compile_Block(unsigned stop);
void Compile_Block(unsigned end);
void Compile_NextInstr(unsigned* offset);
void Compile_SwizzleSrc(Instruction instr, unsigned src_num, SourceRegister src_reg, Gen::X64Reg dest);