cmd/compile: add DWARF reg defs & fix 32-bit location list bug

Before DWARF location lists can be turned on, 3 bugs need
fixing.

This CL addresses two -- lack of register definitions for
various architectures, and bugs on 32-bit platforms.
The third bug comes later.

Passes
GO_GCFLAGS=-dwarflocationlists ./run.bash -no-rebuild
(-no-rebuild because the map dependence causes trouble)

Change-Id: I4223b48ade84763e4b048e4aeb81149f082c7bc7
Reviewed-on: https://go-review.googlesource.com/99255
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

2 files changed, 21 insertions, 6 deletions

diff --git a/src/cmd/internal/obj/arm/a.out.go b/src/cmd/internal/obj/arm/a.out.go
index d4d9510230..358f329b4f 100644
--- a/src/cmd/internal/obj/arm/a.out.go
+++ b/src/cmd/internal/obj/arm/a.out.go
@@ -110,6 +110,20 @@ const (
 	FREGTMP = REG_F15
 )
 
+// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0040b/IHI0040B_aadwarf.pdf
+var ARMDWARFRegisters = map[int16]int16{}
+
+func init() {
+	// f assigns dwarfregisters[from:to] = (base):(step*(to-from)+base)
+	f := func(from, to, base, step int16) {
+		for r := int16(from); r <= to; r++ {
+			ARMDWARFRegisters[r] = step*(r-from) + base
+		}
+	}
+	f(REG_R0, REG_R15, 0, 1)
+	f(REG_F0, REG_F15, 64, 2) // Use d0 through D15, aka S0, S2, ..., S30
+}
+
 const (
 	C_NONE = iota
 	C_REG
diff --git a/src/cmd/internal/obj/arm/obj5.go b/src/cmd/internal/obj/arm/obj5.go
index 2046649e38..82ca301205 100644
--- a/src/cmd/internal/obj/arm/obj5.go
+++ b/src/cmd/internal/obj/arm/obj5.go
@@ -885,10 +885,11 @@ var unaryDst = map[obj.As]bool{
 }
 
 var Linkarm = obj.LinkArch{
-	Arch:       sys.ArchARM,
-	Init:       buildop,
-	Preprocess: preprocess,
-	Assemble:   span5,
-	Progedit:   progedit,
-	UnaryDst:   unaryDst,
+	Arch:           sys.ArchARM,
+	Init:           buildop,
+	Preprocess:     preprocess,
+	Assemble:       span5,
+	Progedit:       progedit,
+	UnaryDst:       unaryDst,
+	DWARFRegisters: ARMDWARFRegisters,
 }