From 12a2e14b6d307a8462e7ad5809369a74cbe7f2d1 Mon Sep 17 00:00:00 2001
From: Stephen Heumann <stephenheumann@gmail.com>
Date: Wed, 12 Oct 2022 19:14:13 -0500
Subject: [PATCH] Follow up peephole optimizations that may enable more
 optimizations.

If one step of peephole optimization produced code that can be further optimized with more peephole optimizations, that additional optimization was not always done. This makes sure the additional optimization is done in several such cases.

This was particularly likely to affect functions containing asm blocks (because CheckLabels would never trigger rescanning in them), but could also occur in other cases.

Here is an example affected by this (generating inefficient code to load a[1]):

#pragma optimize 1
int a[10];
void f(int x) {}
int main(int argc, char **argv) {
        if (argc) return 0;
        f(a[1]);
}
---
 DAG.pas | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/DAG.pas b/DAG.pas
index 0280e8b..3bb3981 100644
--- a/DAG.pas
+++ b/DAG.pas
@@ -604,7 +604,7 @@ var
                      if lab^ = op^.lab^ then
                         same := true;
             end {if}
-         else {if op^.opcode = pc_str then}
+         else if op^.opcode = pc_str then
             if opcode = pc_lod then
                if q = op^.q then
                   if r = op^.r then
@@ -751,11 +751,13 @@ case op^.opcode of			{check for optimizations of this node}
                op^.opcode := pc_inc;
                op^.q := q;
                op^.right := nil;
+               PeepHoleOptimization(opv);
                end {else if}
             else {if q < 0 then} begin
                op^.opcode := pc_dec;
                op^.q := -q;
                op^.right := nil;
+               PeepHoleOptimization(opv);
                end; {else if}
             end {if}
          else if CodesMatch(op^.left, op^.right, false) then begin
@@ -820,6 +822,7 @@ case op^.opcode of			{check for optimizations of this node}
                op^.q := ord(lval);
                op^.right := nil;
                done := true;
+               PeepHoleOptimization(opv);
                end {else if}
             else if (lval > -maxint) and (lval < 0) then begin
                op^.opcode := pc_dec;
@@ -827,6 +830,7 @@ case op^.opcode of			{check for optimizations of this node}
                op^.q := -ord(lval); 
                op^.right := nil;
                done := true;
+               PeepHoleOptimization(opv);
                end; {else if}
             end {if}
          else if CodesMatch(op^.left, op^.right, false) then
@@ -1751,8 +1755,10 @@ case op^.opcode of			{check for optimizations of this node}
                   opv := op^.right;
                   end; {if}
                end {if}
-            else
+            else begin
                op^.opcode := pc_neq;
+               PeepHoleOptimization(opv);
+               end; {else}
             end {if}
          end {if}
       else if op^.left^.opcode = pc_ldc then
@@ -1837,8 +1843,14 @@ case op^.opcode of			{check for optimizations of this node}
                and (op^.right^.qval.lo = 0) and (op^.right^.qval.hi = 0)) then
             begin
             case op^.opcode of
-               pc_leq: op^.opcode := pc_equ;
-               pc_grt: op^.opcode := pc_neq;
+               pc_leq: begin
+                       op^.opcode := pc_equ;
+                       PeepHoleOptimization(opv);
+                       end;
+               pc_grt: begin
+                       op^.opcode := pc_neq;
+                       PeepHoleOptimization(opv);
+                       end;
                pc_les: if not SideEffects(op^.left) then begin
                           op^.right^.optype := cgWord;
                           op^.right^.q := 0;
@@ -1916,6 +1928,7 @@ case op^.opcode of			{check for optimizations of this node}
             else begin
                op^.opcode := pc_neq;
                op^.optype := cgLong;
+               PeepHoleOptimization(opv);
                end; {else}
             end; {if}
          end {if}
@@ -2283,11 +2296,13 @@ case op^.opcode of			{check for optimizations of this node}
             op^.opcode := pc_dec;
             op^.q := q;
             op^.right := nil;
+            PeepHoleOptimization(opv);
             end {else if}
          else {if q < 0) then} begin
             op^.opcode := pc_inc;
             op^.q := -q;
             op^.right := nil;
+            PeepHoleOptimization(opv);
             end; {else if}
          end {if}
       else if op^.left^.opcode in [pc_inc,pc_dec] then
@@ -2338,12 +2353,14 @@ case op^.opcode of			{check for optimizations of this node}
             op^.q := ord(lval);
             op^.right := nil;
             op^.optype := cgLong;
+            PeepHoleOptimization(opv);
             end {else if}
          else if (lval > -maxint) and (lval < 0) then begin
             op^.opcode := pc_inc;
             op^.q := -ord(lval);
             op^.right := nil;
             op^.optype := cgLong;
+            PeepHoleOptimization(opv);
             end; {else if}       
          end; {if}
       end; {case pc_sbl}
@@ -2462,22 +2479,23 @@ case op^.opcode of			{check for optimizations of this node}
       end; {case pc_sro, pc_str}
 
    pc_sto: begin			{pc_sto}
-      if op^.optype in [cgReal,cgDouble,cgExtended,cgComp] then
-         RealStoreOptimizations(op, op^.right);
+      op2 := op^.right;
       if op^.left^.opcode = pc_lao then begin
          op^.q := op^.left^.q;
          op^.lab := op^.left^.lab;
          op^.opcode := pc_sro;
-         op^.left := op^.right;
+         op^.left := op2;
          op^.right := nil;
          end {if}
       else if op^.left^.opcode = pc_lda then begin
          op^.q := op^.left^.q;
          op^.r := op^.left^.r;
          op^.opcode := pc_str;
-         op^.left := op^.right;
+         op^.left := op2;
          op^.right := nil;
          end; {if}
+      if op^.optype in [cgReal,cgDouble,cgExtended,cgComp] then
+         RealStoreOptimizations(op, op2);
       end; {case pc_sto}
 
    pc_sqr: begin			{pc_sqr}