cmd/compile: retrieve Args from registers

in progress; doesn't fully work until they are also passed on
register on the caller side.

For #40724.

Change-Id: I29a6680e60bdbe9d132782530214f2a2b51fb8f6
Reviewed-on: https://go-review.googlesource.com/c/go/+/293394
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 19 insertions, 5 deletions

diff --git a/src/cmd/compile/internal/ssa/expand_calls.go b/src/cmd/compile/internal/ssa/expand_calls.go
index 741d59258b..68fb0581f6 100644
--- a/src/cmd/compile/internal/ssa/expand_calls.go
+++ b/src/cmd/compile/internal/ssa/expand_calls.go
@@ -808,9 +808,9 @@ func (x *expandState) rewriteArgs(v *Value, firstArg int) *Value {
 		}
 		auxI := int64(i - firstArg)
 		aRegs := aux.RegsOfArg(auxI)
-		aOffset := aux.OffsetOfArg(auxI)
 		aType := aux.TypeOfArg(auxI)
 		if a.Op == OpDereference {
+			aOffset := aux.OffsetOfArg(auxI)
 			if a.MemoryArg() != m0 {
 				x.f.Fatalf("Op...LECall and OpDereference have mismatched mem, %s and %s", v.LongString(), a.LongString())
 			}
@@ -821,13 +821,16 @@ func (x *expandState) rewriteArgs(v *Value, firstArg int) *Value {
 			// TODO(register args) this will be more complicated with registers in the picture.
 			mem = x.rewriteDereference(v.Block, x.sp, a, mem, aOffset, aux.SizeOfArg(auxI), aType, pos)
 		} else {
-			if x.debug {
-				fmt.Printf("storeArg %s, %v, %d\n", a.LongString(), aType, aOffset)
-			}
 			var rc registerCursor
 			var result *[]*Value
+			var aOffset int64
 			if len(aRegs) > 0 {
 				result = &allResults
+			} else {
+				aOffset = aux.OffsetOfArg(auxI)
+			}
+			if x.debug {
+				fmt.Printf("storeArg %s, %v, %d\n", a.LongString(), aType, aOffset)
 			}
 			rc.init(aRegs, aux.abiInfo, result)
 			mem = x.storeArgOrLoad(pos, v.Block, x.sp, a, mem, aType, aOffset, 0, rc)
@@ -1213,8 +1216,19 @@ func expandCalls(f *Func) {
 							pa.Offset(), frameOff, v.LongString()))
 					}
 				case 1:
+					r := pa.Registers[0]
+					i := f.ABISelf.FloatIndexFor(r)
+					// TODO seems like this has implications for debugging. How does this affect the location?
+					if i >= 0 { // float PR
+						v.Op = OpArgFloatReg
+					} else {
+						v.Op = OpArgIntReg
+						i = int64(r)
+					}
+					v.AuxInt = i
+
 				default:
-					panic(badVal("Saw unexpeanded OpArg", v))
+					panic(badVal("Saw unexpanded OpArg", v))
 				}
 
 			case OpStaticLECall: