1 files changed, 43 insertions, 32 deletions

diff --git a/archival/libarchive/bz/compress.c b/archival/libarchive/bz/compress.c
index f65076758..462740b6c 100644
--- a/archival/libarchive/bz/compress.c
+++ b/archival/libarchive/bz/compress.c
@@ -158,6 +158,38 @@ void makeMaps_e(EState* s)
 
 
 /*---------------------------------------------------*/
+/*
+ * This bit of code is performance-critical.
+ * On 32bit x86, gcc-6.3.0 was observed to spill ryy_j to stack,
+ * resulting in abysmal performance (x3 slowdown).
+ * Forcing it into a separate function alleviates register pressure,
+ * and spillage no longer happens.
+ * Other versions of gcc do not exhibit this problem, but out-of-line code
+ * seems to be helping them too (code is both smaller and faster).
+ * Therefore NOINLINE is enabled for the entire 32bit x86 arch for now,
+ * without a check for gcc version.
+ */
+static
+#if defined __i386__
+NOINLINE
+#endif
+int inner_loop(uint8_t *yy, uint8_t ll_i)
+{
+        register uint8_t  rtmp;
+        register uint8_t* ryy_j;
+        rtmp  = yy[1];
+        yy[1] = yy[0];
+        ryy_j = &(yy[1]);
+        while (ll_i != rtmp) {
+                register uint8_t rtmp2;
+                ryy_j++;
+                rtmp2  = rtmp;
+                rtmp   = *ryy_j;
+                *ryy_j = rtmp2;
+        }
+        yy[0] = rtmp;
+        return ryy_j - &(yy[0]);
+}
 static NOINLINE
 void generateMTFValues(EState* s)
 {
@@ -165,7 +197,6 @@ void generateMTFValues(EState* s)
         int i;
         int zPend;
         int32_t wr;
-        int32_t EOB;
 
         /*
          * After sorting (eg, here),
@@ -189,15 +220,12 @@ void generateMTFValues(EState* s)
          * compressBlock().
          */
         uint32_t* ptr   = s->ptr;
-        uint8_t*  block = s->block;
-        uint16_t* mtfv  = s->mtfv;
 
         makeMaps_e(s);
-        EOB = s->nInUse+1;
 
         wr = 0;
         zPend = 0;
-        for (i = 0; i <= EOB; i++)
+        for (i = 0; i <= s->nInUse+1; i++)
                 s->mtfFreq[i] = 0;
 
         for (i = 0; i < s->nInUse; i++)
@@ -211,7 +239,7 @@ void generateMTFValues(EState* s)
                 j = ptr[i] - 1;
                 if (j < 0)
                         j += s->nblock;
-                ll_i = s->unseqToSeq[block[j]];
+                ll_i = s->unseqToSeq[s->block[j]];
                 AssertD(ll_i < s->nInUse, "generateMTFValues(2a)");
 
                 if (yy[0] == ll_i) {
@@ -225,15 +253,15 @@ void generateMTFValues(EState* s)
                         while (1) {
 #if 0
                                 if (zPend & 1) {
-                                        mtfv[wr] = BZ_RUNB; wr++;
+                                        s->mtfv[wr] = BZ_RUNB; wr++;
                                         s->mtfFreq[BZ_RUNB]++;
                                 } else {
-                                        mtfv[wr] = BZ_RUNA; wr++;
+                                        s->mtfv[wr] = BZ_RUNA; wr++;
                                         s->mtfFreq[BZ_RUNA]++;
                                 }
 #else /* same as above, since BZ_RUNA is 0 and BZ_RUNB is 1 */
                                 unsigned run = zPend & 1;
-                                mtfv[wr] = run;
+                                s->mtfv[wr] = run;
                                 wr++;
                                 s->mtfFreq[run]++;
 #endif
@@ -247,36 +275,19 @@ void generateMTFValues(EState* s)
                                 goto end;
                         zPend = 0;
                 }
-                {
-                        register uint8_t  rtmp;
-                        register uint8_t* ryy_j;
-                        register uint8_t  rll_i;
-                        rtmp  = yy[1];
-                        yy[1] = yy[0];
-                        ryy_j = &(yy[1]);
-                        rll_i = ll_i;
-                        while (rll_i != rtmp) {
-                                register uint8_t rtmp2;
-                                ryy_j++;
-                                rtmp2  = rtmp;
-                                rtmp   = *ryy_j;
-                                *ryy_j = rtmp2;
-                        }
-                        yy[0] = rtmp;
-                        j = ryy_j - &(yy[0]);
-                        mtfv[wr] = j+1;
-                        wr++;
-                        s->mtfFreq[j+1]++;
-                }
+                j = inner_loop(yy, ll_i);
+                s->mtfv[wr] = j+1;
+                wr++;
+                s->mtfFreq[j+1]++;
         }
 
         i = -1;
         if (zPend > 0)
                 goto process_zPend; /* "process it and come back here" */
  end:
-        mtfv[wr] = EOB;
+        s->mtfv[wr] = s->nInUse+1;
         wr++;
-        s->mtfFreq[EOB]++;
+        s->mtfFreq[s->nInUse+1]++;
 
         s->nMTF = wr;
 }