[dev.ssa] cmd/compile: everything is live and reachable after regalloc

This CL makes function printing and HTML generation
accurate after regalloc.

Prior to this CL, text and HTML function outputs
showed live values and blocks as dead.

Change-Id: I70669cd8641af841447fc5d2ecbd754b281356f0
Reviewed-on: https://go-review.googlesource.com/13812
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/compile/internal/ssa/deadcode.go b/src/cmd/compile/internal/ssa/deadcode.go
index 8c306c8412e5b1b80f50ba768a040423c2c185ea..5ff082baff13ce694e74528b35925914fc69394e 100644 (file)
--- a/src/cmd/compile/internal/ssa/deadcode.go
+++ b/src/cmd/compile/internal/ssa/deadcode.go
@@ -6,6 +6,20 @@ package ssa
 
 // findlive returns the reachable blocks and live values in f.
 func findlive(f *Func) (reachable []bool, live []bool) {
+       // After regalloc, consider all blocks and values to be reachable and live.
+       // See the comment at the top of regalloc.go and in deadcode for details.
+       if f.RegAlloc != nil {
+               reachable = make([]bool, f.NumBlocks())
+               for i := range reachable {
+                       reachable[i] = true
+               }
+               live = make([]bool, f.NumValues())
+               for i := range live {
+                       live[i] = true
+               }
+               return reachable, live
+       }
+
        // Find all reachable basic blocks.
        reachable = make([]bool, f.NumBlocks())
        reachable[f.Entry.ID] = true