From a92f6bf42e547c6978e4e317b4feb2c6610cf518 Mon Sep 17 00:00:00 2001
From: Walter Bright <walter@walterbright.com>
Date: Tue, 23 Aug 2011 14:56:25 -0700
Subject: [PATCH] Issue 6505 - Wrong code for expression involving 8 floats,
 only with -O

---
 src/backend/cgen.c    | 20 ++++++++++++++++++++
 src/backend/cgsched.c |  9 ++++++++-
 src/backend/cod1.c    |  2 ++
 src/backend/code.h    |  2 ++
 4 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/backend/cgen.c b/src/backend/cgen.c
index a261f2185005..1990cce0bf63 100644
--- a/src/backend/cgen.c
+++ b/src/backend/cgen.c
@@ -512,6 +512,26 @@ code *genadjesp(code *c, int offset)
         return c;
 }
 
+/********************************
+ * Generate 'instruction' which tells the scheduler that the fpu stack has
+ * changed.
+ */
+
+code *genadjfpu(code *c, int offset)
+{   code cs;
+
+    if (!I16 && offset)
+    {
+        cs.Iop = ESCAPE | ESCadjfpu;
+        cs.Iflags = 0;
+        cs.Irex = 0;
+        cs.IEV2.Vint = offset;
+        return gen(c,&cs);
+    }
+    else
+        return c;
+}
+
 /********************************
  * Generate 'nop'
  */
diff --git a/src/backend/cgsched.c b/src/backend/cgsched.c
index 939c402e8fd7..5db85d1e100c 100644
--- a/src/backend/cgsched.c
+++ b/src/backend/cgsched.c
@@ -1348,6 +1348,11 @@ STATIC void getinfo(Cinfo *ci,code *c)
             c->Iflags |= CFpsw;
             break;
 
+        case ESCAPE:
+            if (c->Iop == (ESCAPE | ESCadjfpu))
+                ci->fpuadjust = c->IEV2.Vint;
+            break;
+
         case 0xD0:
         case 0xD1:
         case 0xD2:
@@ -2691,7 +2696,9 @@ code *schedule(code *c,regm_t scratch)
     sch.initialize(0);                  // initialize scheduling table
     while (c)
     {
-        if ((c->Iop == NOP || (c->Iop & 0xFF) == ESCAPE || c->Iflags & CFclassinit) &&
+        if ((c->Iop == NOP ||
+             ((c->Iop & 0xFF) == ESCAPE && c->Iop != (ESCAPE | ESCadjfpu)) ||
+             c->Iflags & CFclassinit) &&
             !(c->Iflags & (CFtarg | CFtarg2)))
         {   code *cn;
 
diff --git a/src/backend/cod1.c b/src/backend/cod1.c
index d55fb10bd2f2..1c7a4d3bd070 100644
--- a/src/backend/cod1.c
+++ b/src/backend/cod1.c
@@ -3081,6 +3081,7 @@ STATIC code * funccall(elem *e,unsigned numpara,unsigned numalign,regm_t *pretre
 
     if (retregs & mST0)
     {
+        c = genadjfpu(c, 1);
         if (*pretregs)                  // if we want the result
         {   //assert(stackused == 0);
             push87();                   // one item on 8087 stack
@@ -3092,6 +3093,7 @@ STATIC code * funccall(elem *e,unsigned numpara,unsigned numalign,regm_t *pretre
     }
     else if (retregs & mST01)
     {
+        c = genadjfpu(c, 2);
         if (*pretregs)                  // if we want the result
         {   assert(stackused == 0);
             push87();
diff --git a/src/backend/code.h b/src/backend/code.h
index cdbc99d20f18..3682ddd4470b 100644
--- a/src/backend/code.h
+++ b/src/backend/code.h
@@ -244,6 +244,7 @@ extern regm_t BYTEREGS;
     #define ESCframeptr (10 << 8)      // replace with load of frame pointer
     #define ESCdctor    (11 << 8)      // D object is constructed
     #define ESCddtor    (12 << 8)      // D object is destructed
+    #define ESCadjfpu   (13 << 8)      // adjust fpustackused by IEV2.Vint
 
 #define ASM     0x36    // string of asm bytes, actually an SS: opcode
 
@@ -876,6 +877,7 @@ code *genlinnum(code *,Srcpos);
 void cgen_linnum(code **pc,Srcpos srcpos);
 void cgen_prelinnum(code **pc,Srcpos srcpos);
 code *genadjesp(code *c, int offset);
+code *genadjfpu(code *c, int offset);
 code *gennop(code *);
 code *genshift(code *);
 code *movregconst (code *c , unsigned reg , targ_size_t value , regm_t flags );