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authorJohannes Stoelp <johannes.stoelp@gmail.com>2024-03-18 22:59:18 +0100
committerJohannes Stoelp <johannes.stoelp@gmail.com>2024-03-18 22:59:18 +0100
commit7653ced7e8ce18b9ada2b666c63832007f8becf2 (patch)
tree3d0af2d9a2d26eeab02cc422195bc4f4efe3c744 /examples
parentf0b70fe1774a0da0cd6148fb28b933d6dfb122f8 (diff)
downloadjuicebox-asm-main.tar.gz
juicebox-asm-main.zip
tiny_vm: replace control flow insns with cmovz insnHEADmain
Diffstat (limited to 'examples')
-rw-r--r--examples/tiny_vm.rs14
1 files changed, 7 insertions, 7 deletions
diff --git a/examples/tiny_vm.rs b/examples/tiny_vm.rs
index 86f5eaf..1f4c653 100644
--- a/examples/tiny_vm.rs
+++ b/examples/tiny_vm.rs
@@ -38,7 +38,7 @@
use juicebox_asm::insn::*;
use juicebox_asm::Runtime;
-use juicebox_asm::{Asm, Imm16, Imm64, Label, MemOp, Reg16, Reg64};
+use juicebox_asm::{Asm, Imm16, Imm64, MemOp, Reg16, Reg64};
/// A guest physical address.
pub struct PhysAddr(pub u16);
@@ -330,13 +330,13 @@ impl TinyVm {
TinyInsn::BranchZero(a, disp) => {
bb.cmp(reg_op(a), Imm16::from(0u16));
bb.mov(Reg64::rax, Imm64::from(bb_icnt()));
- bb.mov(Reg64::rdx, Imm64::from(reenter_pc(disp)));
-
- let mut skip_next_pc = Label::new();
- // If register is zero, skip setting next pc as reenter pc.
- bb.jz(&mut skip_next_pc);
+ // Default fall-through PC (branch not taken).
bb.mov(Reg64::rdx, Imm64::from(reenter_pc(pc)));
- bb.bind(&mut skip_next_pc);
+
+ // Conditionally update PC if condition is ZERO (branch taken).
+ bb.mov(Reg64::r11, Imm64::from(reenter_pc(disp)));
+ bb.cmovz(Reg64::rdx, Reg64::r11);
+
bb.ret();
break 'outer;
}