5l/6l/8l: undo spadj cleanup at ARET for following instructions in the same stackframe.

5l was already correct, clarified comment and added diags for unmaintained code.

R=rsc
CC=golang-dev
https://golang.org/cl/4277070

diff --git a/src/cmd/5l/noop.c b/src/cmd/5l/noop.c
index a5e66f0380fa18ae8acbeaa549f43267b0a7b5c6..bdcc3cad897a4f42ba0139a207c00d687b1df2b1 100644 (file)
--- a/src/cmd/5l/noop.c
+++ b/src/cmd/5l/noop.c
@@ -364,14 +364,14 @@ noops(void)
                                        p = appendp(p);
                                        p->as = ABL;
                                        p->scond = C_SCOND_LO;
-                                       p->to.type = D_BRANCH;
+                                       p->to.type = D_BRANCH;
                                        p->to.sym = symmorestack;
                                        p->cond = pmorestack;
        
                                        // MOVW.W               R14,$-autosize(SP)
                                        p = appendp(p);
                                        p->as = AMOVW;
-                                       p->scond |= C_WBIT;
+                                       p->scond |= C_WBIT;
                                        p->from.type = D_REG;
                                        p->from.reg = REGLINK;
                                        p->to.type = D_OREG;
@@ -413,14 +413,14 @@ noops(void)
                                        // BL           runtime.morestack(SB) // modifies LR
                                        p = appendp(p);
                                        p->as = ABL;
-                                       p->to.type = D_BRANCH;
+                                       p->to.type = D_BRANCH;
                                        p->to.sym = symmorestack;
                                        p->cond = pmorestack;
        
                                        // MOVW.W               R14,$-autosize(SP)
                                        p = appendp(p);
                                        p->as = AMOVW;
-                                       p->scond |= C_WBIT;
+                                       p->scond |= C_WBIT;
                                        p->from.type = D_REG;
                                        p->from.reg = REGLINK;
                                        p->to.type = D_OREG;
@@ -450,6 +450,8 @@ noops(void)
                                        }
                                }
                                if(thumb){
+                                       diag("thumb not maintained");
+                                       errorexit();
                                        if(cursym->text->mark & LEAF){
                                                if(autosize){
                                                        p->as = AADD;
@@ -481,7 +483,7 @@ noops(void)
                                                        q->to.type = D_REG;
                                                        q->to.reg = REGSP;
                                                        q->link = p->link;
-                                                       p->link =       q;
+                                                       p->link =       q;
                                                }
                                                else
                                                        q = p;
@@ -492,6 +494,8 @@ noops(void)
                                        break;
                                }
                                if(foreign) {
+                                       diag("foreign not maintained");
+                                       errorexit();
 // if(foreign) print("ABXRET 3 %s\n", cursym->name);
 #define        R       1
                                        p->as = AMOVW;
@@ -530,7 +534,9 @@ noops(void)
                                        p->from.reg = REGSP;
                                        p->to.type = D_REG;
                                        p->to.reg = REGPC;
-                                       // no spadj because it doesn't fall through
+                                       // If there are instructions following
+                                       // this ARET, they come from a branch
+                                       // with the same stackframe, so no spadj.
                                }
                                break;
        

diff --git a/src/cmd/6l/pass.c b/src/cmd/6l/pass.c
index 8fda943923aae75a7cc35f5d5ab190c877dd1e23..0b0ee1253cd0c9db99f1190bedba32f84b398684 100644 (file)
--- a/src/cmd/6l/pass.c
+++ b/src/cmd/6l/pass.c
@@ -274,10 +274,10 @@ patch(void)
                if(HEADTYPE == Hwindows) { 
                        // Windows
                        // Convert
-                       //   op   n(GS), reg
+                       //   op   n(GS), reg
                        // to
                        //   MOVL 0x58(GS), reg
-                       //   op   n(reg), reg
+                       //   op   n(reg), reg
                        // The purpose of this patch is to fix some accesses
                        // to extern register variables (TLS) on Windows, as
                        // a different method is used to access them.
@@ -674,6 +674,11 @@ dostkoff(void)
                                p->spadj = -autoffset;
                                p = appendp(p);
                                p->as = ARET;
+                               // If there are instructions following
+                               // this ARET, they come from a branch
+                               // with the same stackframe, so undo
+                               // the cleanup.
+                               p->spadj = +autoffset;
                        }
                }
        }

diff --git a/src/cmd/8l/pass.c b/src/cmd/8l/pass.c
index 294926f2937442fbb7d4940814be539998e3e773..28589b66a16c158c5309ce2ba523acb595c7d9d9 100644 (file)
--- a/src/cmd/8l/pass.c
+++ b/src/cmd/8l/pass.c
@@ -614,14 +614,17 @@ dostkoff(void)
                                diag("unbalanced PUSH/POP");
        
                        if(autoffset) {
-                               q = p;
+                               p->as = AADJSP;
+                               p->from.type = D_CONST;
+                               p->from.offset = -autoffset;
+                               p->spadj = -autoffset;
                                p = appendp(p);
                                p->as = ARET;
-       
-                               q->as = AADJSP;
-                               q->from.type = D_CONST;
-                               q->from.offset = -autoffset;
-                               p->spadj = -autoffset;
+                               // If there are instructions following
+                               // this ARET, they come from a branch
+                               // with the same stackframe, so undo
+                               // the cleanup.
+                               p->spadj = +autoffset;
                        }
                }
        }