From 33e0d056453ee1cb66bf210f21b786f0f7ed70ab Mon Sep 17 00:00:00 2001
From: Benjamin Bouvier <public@benj.me>
Date: Mon, 6 Jul 2020 15:42:31 +0200
Subject: [PATCH] machinst x64: have cmov modify its destination operand;

This is tricky: the control flow implicitly implied by the operand makes
it so that the output register may be undefined, if we mark it only as a
"def". Make it a "mod" instead, which matches our usage in the codebase,
and will make it crash if the output operand isn't unconditionally
defined before the instruction.
---
 cranelift/codegen/src/isa/x64/inst/mod.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cranelift/codegen/src/isa/x64/inst/mod.rs b/cranelift/codegen/src/isa/x64/inst/mod.rs
index bb50f85f11..fc01c3e832 100644
--- a/cranelift/codegen/src/isa/x64/inst/mod.rs
+++ b/cranelift/codegen/src/isa/x64/inst/mod.rs
@@ -905,7 +905,7 @@ fn x64_get_regs(inst: &Inst, collector: &mut RegUsageCollector) {
         }
         Inst::Cmove { src, dst, .. } => {
             src.get_regs_as_uses(collector);
-            collector.add_def(*dst);
+            collector.add_mod(*dst);
         }
         Inst::Push64 { src } => {
             src.get_regs_as_uses(collector);
@@ -1126,7 +1126,7 @@ fn x64_map_regs<RUM: RegUsageMapper>(inst: &mut Inst, mapper: &RUM) {
             ..
         } => {
             src.map_uses(mapper);
-            map_def(mapper, dst)
+            map_mod(mapper, dst)
         }
         Inst::Push64 { ref mut src } => src.map_uses(mapper),
         Inst::Pop64 { ref mut dst } => {