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[dev.ssa] cmd/compile: improve special register error checking

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Provide better diagnostic messages.

Use an int for numRegs comparisons,
to avoid asking whether a uint8 is > 255.

Change-Id: I33ae193ce292b24b369865abda3902c3207d7d3f
Reviewed-on: https://go-review.googlesource.com/24135
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2016-06-15 10:07:16 -07:00
parent d0fa6c2f9e
commit a2beee000b
1 changed files with 23 additions and 8 deletions
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31
src/cmd/compile/internal/ssa/regalloc.go
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@ -439,21 +439,36 @@ func (s *regAllocState) allocValToReg(v *Value, mask regMask, nospill bool, line
func (s *regAllocState) init(f *Func) {
s.f = f
s.registers = f.Config.registers
s.numRegs = register(len(s.registers))
if s.numRegs > noRegister || s.numRegs > register(unsafe.Sizeof(regMask(0))*8) {
panic("too many registers")
if nr := len(s.registers); nr == 0 || nr > int(noRegister) || nr > int(unsafe.Sizeof(regMask(0))*8) {
s.f.Fatalf("bad number of registers: %d", nr)
} else {
s.numRegs = register(nr)
}
// Locate SP, SB, and g registers.
s.SPReg = noRegister
s.SBReg = noRegister
s.GReg = noRegister
for r := register(0); r < s.numRegs; r++ {
if s.registers[r].Name() == "SP" {
switch s.registers[r].Name() {
case "SP":
s.SPReg = r
}
if s.registers[r].Name() == "SB" {
case "SB":
s.SBReg = r
}
if s.registers[r].Name() == "g" {
case "g":
s.GReg = r
}
}
// Make sure we found all required registers.
switch noRegister {
case s.SPReg:
s.f.Fatalf("no SP register found")
case s.SBReg:
s.f.Fatalf("no SB register found")
case s.GReg:
if f.Config.hasGReg {
s.f.Fatalf("no g register found")
}
}
// Figure out which registers we're allowed to use.
s.allocatable = s.f.Config.gpRegMask | s.f.Config.fpRegMask | s.f.Config.flagRegMask