<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>On Nov 26, 2007, at 23:40, Chris Lattner wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">On Nov 26, 2007, at 11:30 AM, Gordon Henriksen wrote:<br><br><blockquote type="cite"><blockquote type="cite"></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span class="Apple-style-span" style="-webkit-text-stroke-width: -1; ">1. The ocaml exception model is quite unique; emulating it seems unlikely. DWARF exceptions are a suitable but incompatible replacement.</span></blockquote></blockquote><blockquote type="cite"><br>Can you explain how the ocaml exception model works?<br></blockquote></div><div apple-content-edited="true"><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><br class="webkit-block-placeholder"></div><div style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; ">Sure. With ocamlopt's model, <font class="Apple-style-span" face="Courier"><b>try</b></font> has cost only slightly higher than a function call and <font class="Apple-style-span" face="Courier"><b>raise</b></font> has cost only slightly higher than return. I'm not concerned with the bytecode interpreter and compiler, ocamlc and ocamlrun.</span></span></div><div style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><br class="webkit-block-placeholder"></div><div style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><br class="webkit-block-placeholder"></div><div style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; ">As Daniel Berlin pointed out on IRC, the language model is trivial. It has just three exception-handling primitives:</span></span></div><div style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><br class="webkit-block-placeholder"></div></span></div><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><i>matching</i> ::= <i>pattern</i> ‘<font class="Apple-style-span" color="#000000"><font class="Apple-style-span" face="Courier"><b>-></b></font></font>’ <i>expr</i> ( ‘<font class="Apple-style-span" face="Courier"><b>|</b></font>’ <i>pattern</i> ‘<font class="Apple-style-span" face="Courier"><b>-></b></font>’ <i>expr</i> )*<br><br><font class="Apple-style-span" face="'Courier New'"><b>raise</b></font> <span class="Apple-style-span" style="font-style: italic; ">expr</span><br><font class="Apple-style-span" face="'Courier New'"><b><font class="Apple-style-span" color="#000000"><font class="Apple-style-span" face="Courier">try</font></font></b></font> <i>expr</i> <font class="Apple-style-span" color="#000000"><font class="Apple-style-span" face="Courier"><b>with</b></font></font> <i>matching</i><br><font class="Apple-style-span" face="'Courier New'"><b>exception</b></font> <i>id</i> ( <i>tuple-type-expr</i> )?</blockquote><div apple-content-edited="true"><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "></div><div style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><div><br class="webkit-block-placeholder"></div></div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><font class="Apple-style-span" face="Courier"><b>exception</b></font> declares an exception type. For the purposes of this discussion, exception values are just heap pointers. <font class="Apple-style-span" face="Courier"><b>raise</b></font> and <font class="Apple-style-span" face="Courier"><b>with</b></font> only accept expressions of an exception type.</div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br class="webkit-block-placeholder"></div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><font class="Apple-style-span" face="Courier"><b>raise</b></font> unwinds the stack, submitting <i>expr</i> to the first matching <i>pattern</i> in the nearest enclosing <font class="Apple-style-span" face="Courier"><b>try</b></font>-<font class="Apple-style-span" face="Courier"><b>with</b></font>. The runtime provides a catch-all at startup which terminates the program. The <i>matching</i> expression is sufficient to implement finally (<font class="Apple-style-span" face="Courier">x -> <i>expr</i></font>) and catch-all (<font class="Apple-style-span" face="Courier">x -> <i>expr</i>; raise x</font>). Each finally expression requires its own <font class="Apple-style-span" face="Courier"><b>try</b></font>-<font class="Apple-style-span" face="Courier"><b>with</b></font> expression.</div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br class="webkit-block-placeholder"></div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br></div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">The codegen for <span class="Apple-style-span" style="font-family: Courier; font-weight: bold; ">raise</span> is simple. It just reads a saved return address from the <font class="Apple-style-span" face="Courier">caml_exception_pointer</font> global and returns through several stack frames in one go. The expression <font class="Apple-style-span" face="Courier">raise expr</font> is compiled as such:</div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br class="webkit-block-placeholder"></div></span></div><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; Store the exception value in the return register.</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier">$r1 = ...</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><br class="webkit-block-placeholder"></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" color="#008040" face="Courier">; Change the stack pointer.</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><span class="Apple-style-span" style="font-family: Courier; ">load $sp <- 0(caml_exception_pointer)</span></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><br></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><span class="Apple-style-span" style="font-family: 'Trebuchet MS'; "><font class="Apple-style-span" color="#008040" face="Courier">; The stack now contains:</font></span></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><span class="Apple-style-span" style="font-family: 'Trebuchet MS'; "><font class="Apple-style-span" color="#008040" face="Courier"></font><div><font class="Apple-style-span" color="#008040" face="Courier">; ... rest of stack ...</font></div><div><font class="Apple-style-span" color="#008040" face="Courier">; return address</font></div><div><font class="Apple-style-span" color="#008040" face="Courier">; old caml_exception_pointer</font></div><div><font class="Apple-style-span" color="#008040" face="Courier">; Restore caml_exception_pointer.<br><span class="Apple-style-span" style="color: rgb(0, 0, 0); font-family: 'Trebuchet MS'; "><span class="Apple-style-span" style="font-family: Courier; ">pop 0(caml_exception_pointer)</span></span></font></div></span></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><br class="webkit-block-placeholder"></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><span class="Apple-style-span" style="color: rgb(0, 128, 64); font-family: Courier; ">; Jump straight to the nearest landing pad.</span></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">ret</font></blockquote><div apple-content-edited="true"><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br></div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">The <font class="Apple-style-span" face="Courier"><b>try</b></font>-<font class="Apple-style-span" face="Courier"><b>with</b></font> expression is where the trickery lies. The expression <font class="Apple-style-span" face="Courier">try</font><font class="Apple-style-span" face="Courier"> </font><i><font class="Apple-style-span" face="Courier">body</font></i><font class="Apple-style-span" face="Courier"> </font><font class="Apple-style-span" face="Courier">with</font><font class="Apple-style-span" face="Courier"> </font><i><font class="Apple-style-span" face="Courier">pattern1</font></i><font class="Apple-style-span" face="Courier"> -> <i>catch1</i> | <i>patternN</i> -> <i>catchN</i></font> is compiled to:</div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br></div></span></div><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; 'Call' a label within the function.</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">call try_block</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><br class="webkit-block-placeholder"></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; This is the landing pad. The exception is in the return register.</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" color="#008040" face="Courier"><br class="webkit-block-placeholder"></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; Try to match a handler.</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">$r2 = $1 matches <i>pattern1</i></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">branch to handler1_block if $r2</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><br class="webkit-block-placeholder"></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier">$r2 = $1 matches <i>patternN</i></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><span class="Apple-style-span" style="font-family: Courier; ">branch to handlerN_block if $r2</span></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><br class="webkit-block-placeholder"></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; If no handler matched, re-raise the exception.</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">load $sp <- 0(caml_exception_pointer)</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">pop 0(caml_exception_pointer)</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><span class="Apple-style-span" style="font-family: Courier; ">ret</span></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><br></font></blockquote><span class="Apple-style-span" style="font-family: Courier; ">handler1_block:</span><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><span class="Apple-style-span" style="font-family: Courier; ">$r1 = <i>catch1</i></span></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">jump to after_block</font></blockquote><font class="Apple-style-span" face="Courier"><div>handlerN_block:</div></font><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><i><span class="Apple-style-span" style="font-family: 'Trebuchet MS'; font-style: normal; "><span class="Apple-style-span" style="font-family: Courier; ">$r1 = <i>catchN</i><i><br></i></span><font class="Apple-style-span" face="Courier">jump to after_block</font><font class="Apple-style-span" face="Courier"></font></span><font class="Apple-style-span" face="Courier"></font></i></font></blockquote><div><font class="Apple-style-span" face="Courier"><br class="webkit-block-placeholder"></font></div><div><font class="Apple-style-span" face="Courier">try_block:</font><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; Save caml_exception_pointer on the stack.</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><span class="Apple-style-span" style="font-family: Courier; ">push 0(caml_exception_pointer)</span></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" color="#008040" face="Courier"><br class="webkit-block-placeholder"></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; The top of the stack is now what raise expects:</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" color="#008040" face="Courier">; ... rest of stack ...</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; return address</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; old caml_exception_pointer</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" color="#008040" face="Courier">; Save $sp into caml_exception_poointer.</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">store $sp -> 0(caml_exception_pointer) </font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><br class="webkit-block-placeholder"></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; Generate try body here.</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">$r1 = body<i><font class="Apple-style-span" color="#008040"> </font><span class="Apple-style-span" style="font-style: normal; "><font class="Apple-style-span" color="#008040">; n.b.: use increased stack offsets to access locals.</font></span></i></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><div><font class="Apple-style-span" face="Courier"><i><br class="webkit-block-placeholder"></i></font></div></blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; Restore the saved value of caml_exception_pointer.</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">pop 0(caml_exception_pointer)</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><br class="webkit-block-placeholder"></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; Resume to the normal flow of execution by undoing the stack </font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; adjustments made by call and falling through. A normal 'ret'</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; would jump into the exception handler, which we don't want!</font></font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier">pop</font></blockquote><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><br></blockquote><font class="Apple-style-span" face="Courier">after_block:<br class="webkit-block-placeholder"></font><blockquote class="webkit-indent-blockquote" style="margin: 0 0 0 40px; border: none; padding: 0px;"><font class="Apple-style-span" face="Courier"><font class="Apple-style-span" color="#008040">; Either the exception was handled, or none was raised.</font></font></blockquote><div apple-content-edited="true"><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br></div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">— Gordon</div></span></div><div apple-content-edited="true"> </div><br></div></body></html>