[llvm-commits] [llvm] r61239 - in /llvm/trunk: docs/LangRef.html include/llvm/Attributes.h lib/Analysis/BasicAliasAnalysis.cpp test/Analysis/BasicAA/nocapture.ll

Bill Wendling isanbard at gmail.com
Fri Dec 19 00:02:46 PST 2008


Nicholas,

This is causing more failures:

Running /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmCore/test/ 
Analysis/BasicAA/dg.exp ...
FAIL: /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmCore/test/ 
Analysis/BasicAA/nocapture.ll
Failed with exit(1) at line 1
while running:  llvm-as < /Volumes/Sandbox/Buildbot/llvm/full-llvm/ 
build/llvmCore/test/Analysis/BasicAA/nocapture.ll |  opt -basicaa -gvn  
-instcombine |  llvm-dis | /usr/bin/grep {ret i32 0}
llvm-as: <stdin>:3,0: <stdin>:3: error: syntax error, unexpected  
$undefined, expecting ')' while reading token: 'n'
opt: Invalid bitcode signature
llvm-dis: Invalid bitcode signature

Running /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmCore/test/ 
FrontendC/dg.exp ...
FAIL: /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmCore/test/ 
FrontendC/2002-02-13-UnnamedLocal.c
Failed with signal(SIGABRT) at line 1
while running: /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/ 
llvmgcc42.roots/llvmgcc42~dst/Developer/usr/bin/llvm-gcc-4.2 -fstrict- 
aliasing -Wstrict-aliasing -I/usr/include/c++/4.0.0/i686-apple-darwin9  
-I/usr/include/c++/4.0.0 -emit-llvm -w -S /Volumes/Sandbox/Buildbot/ 
llvm/full-llvm/build/llvmCore/test/FrontendC/2002-02-13-UnnamedLocal.c  
-o - |  llvm-as -f -o /dev/null
Assertion failed: (isPowerOf2_32(i) && "Alignment must be a power of  
two."), function constructAlignmentFromInt, file /Volumes/Sandbox/ 
Buildbot/llvm/full-llvm/build/llvmCore/include/llvm/Attributes.h, line  
86.
0   llvm-as           0x0017999f llvm::sys::SetInterruptFunction(void  
(*)()) + 591
1   libSystem.B.dylib 0x91e592bb _sigtramp + 43
2   libSystem.B.dylib 0xffffffff _sigtramp + 1847225711
3   libSystem.B.dylib 0x91ecd23a raise + 26
4   libSystem.B.dylib 0x91ed9679 abort + 73
5   libSystem.Bmake[1]: *** [check-local] Error 1
make: *** [check] Error 2

This is on Darwin x86.

-bw

On Dec 18, 2008, at 10:39 PM, Nick Lewycky wrote:

> Author: nicholas
> Date: Fri Dec 19 00:39:12 2008
> New Revision: 61239
>
> URL: http://llvm.org/viewvc/llvm-project?rev=61239&view=rev
> Log:
> Resubmit support for the 'nocapture' attribute.
>
> The problematic part of this patch is that we were out of attribute  
> bits,
> requiring some fancy bit hacking to make it fit (by shrinking  
> alignment)
> without breaking existing users or the file format.
>
> This change will require users to rebuild llvm-gcc to match llvm.
>
> Added:
>    llvm/trunk/test/Analysis/BasicAA/nocapture.ll
> Modified:
>    llvm/trunk/docs/LangRef.html
>    llvm/trunk/include/llvm/Attributes.h
>    llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
>
> Modified: llvm/trunk/docs/LangRef.html
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.html?rev=61239&r1=61238&r2=61239&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/docs/LangRef.html (original)
> +++ llvm/trunk/docs/LangRef.html Fri Dec 19 00:39:12 2008
> @@ -894,9 +894,15 @@
>     parameter.  The caller is responsible for ensuring that this is  
> the
>     case. On a function return value, <tt>noalias</tt> additionally  
> indicates
>     that the pointer does not alias any other pointers visible to the
> -    caller. Note that this applies only to pointers that can be  
> used to actually
> -    load/store a value: NULL, unique pointers from malloc(0), and  
> freed pointers
> -    are considered to not alias anything.</dd>
> +    caller. For further details, please see the discussion of the  
> NoAlias
> +    response in
> +    <a href="http://llvm.org/docs/AliasAnalysis.html#MustMayNo">alias
> +    analysis</a>.</dd>
> +
> +    <dt><tt>nocapture</tt></dt>
> +    <dd>This indicates that the callee does not make any copies of  
> the pointer
> +    that outlive the callee itself. This is not a valid attribute  
> for return
> +    values.</dd>
>
>     <dt><tt>nest</tt></dt>
>     <dd>This indicates that the pointer parameter can be excised  
> using the
>
> Modified: llvm/trunk/include/llvm/Attributes.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Attributes.h?rev=61239&r1=61238&r2=61239&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/include/llvm/Attributes.h (original)
> +++ llvm/trunk/include/llvm/Attributes.h Fri Dec 19 00:39:12 2008
> @@ -15,6 +15,7 @@
> #ifndef LLVM_ATTRIBUTES_H
> #define LLVM_ATTRIBUTES_H
>
> +#include "llvm/Support/MathExtras.h"
> #include <cassert>
> #include <string>
>
> @@ -23,7 +24,7 @@
>
> /// Attributes - A bitset of attributes.
> typedef unsigned Attributes;
> -
> +
> namespace Attribute {
>
> /// Function parameters and results can have attributes to indicate  
> how they
> @@ -44,16 +45,18 @@
> const Attributes Nest      = 1<<8;  ///< Nested function static chain
> const Attributes ReadNone  = 1<<9;  ///< Function does not access  
> memory
> const Attributes ReadOnly  = 1<<10; ///< Function only reads from  
> memory
> -const Attributes NoInline        = 1<<11; // inline=never
> -const Attributes AlwaysInline    = 1<<12; // inline=always
> -const Attributes OptimizeForSize = 1<<13; // opt_size
> -const Attributes StackProtect    = 1<<14; // Stack protection.
> -const Attributes StackProtectReq = 1<<15; // Stack protection  
> required.
> -const Attributes Alignment = 0xffff<<16; ///< Alignment of  
> parameter (16 bits)
> -                                    // 0 = unknown, else in clear  
> (not log)
> -
> +const Attributes NoInline        = 1<<11; ///< inline=never
> +const Attributes AlwaysInline    = 1<<12; ///< inline=always
> +const Attributes OptimizeForSize = 1<<13; ///< opt_size
> +const Attributes StackProtect    = 1<<14; ///< Stack protection.
> +const Attributes StackProtectReq = 1<<15; ///< Stack protection  
> required.
> +const Attributes Alignment = 31<<16; ///< Alignment of parameter (5  
> bits)
> +                                     // stored as log2 of alignment  
> with +1 bias
> +                                     // 0 means unaligned different  
> from align 1
> +const Attributes NoCapture = 1<<21; ///< Function creates no  
> aliases of pointer
> +
> /// @brief Attributes that only apply to function parameters.
> -const Attributes ParameterOnly = ByVal | Nest | StructRet;
> +const Attributes ParameterOnly = ByVal | Nest | StructRet |  
> NoCapture;
>
> /// @brief Attributes that only apply to function.
> const Attributes FunctionOnly = NoReturn | NoUnwind | ReadNone |  
> ReadOnly |
> @@ -64,7 +67,7 @@
>
> /// @brief Attributes that are mutually incompatible.
> const Attributes MutuallyIncompatible[4] = {
> -  ByVal | InReg | Nest  | StructRet,
> +  ByVal | InReg | Nest | StructRet,
>   ZExt  | SExt,
>   ReadNone | ReadOnly,
>   NoInline | AlwaysInline
> @@ -76,7 +79,13 @@
> /// This turns an int alignment (a power of 2, normally) into the
> /// form used internally in Attributes.
> inline Attributes constructAlignmentFromInt(unsigned i) {
> -  return (i << 16);
> +  // Default alignment, allow the target to define how to align it.
> +  if (i == 0)
> +    return 0;
> +
> +  assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
> +  assert(i <= 0x40000000 && "Alignment too large.");
> +  return (Log2_32(i)+1) << 16;
> }
>
> /// The set of Attributes set in Attributes is converted to a
> @@ -175,7 +184,11 @@
>   /// getParamAlignment - Return the alignment for the specified  
> function
>   /// parameter.
>   unsigned getParamAlignment(unsigned Idx) const {
> -    return (getAttributes(Idx) & Attribute::Alignment) >> 16;
> +    Attributes Align = getAttributes(Idx) & Attribute::Alignment;
> +    if (Align == 0)
> +      return 0;
> +
> +    return 1ull << ((Align >> 16) - 1);
>   }
>
>   /// hasAttrSomewhere - Return true if the specified attribute is  
> set for at
>
> Modified: llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp?rev=61239&r1=61238&r2=61239&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp (original)
> +++ llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp Fri Dec 19  
> 00:39:12 2008
> @@ -63,12 +63,23 @@
>       // callees could modify it.
>       break; // next use
>     case Instruction::Call:
> -      // If the call is to a few known safe intrinsics, we know  
> that it does
> -      // not escape.
> -      // TODO: Eventually just check the 'nocapture' attribute.
> -      if (!isa<MemIntrinsic>(I))
> -        return true;
> -      break;  // next use
> +      // If the argument to the call has the nocapture attribute,  
> then the call
> +      // may store or load to the pointer, but it cannot escape.
> +      if (cast<CallInst>(I)->paramHasAttr(UI.getOperandNo(),
> +                                          Attribute::NoCapture))
> +        continue;
> +
> +      // FIXME: MemIntrinsics should have their operands marked  
> nocapture!
> +      if (isa<MemIntrinsic>(I))
> +        continue;  // next use
> +      return true;
> +    case Instruction::Invoke:
> +      // If the argument to the call has the nocapture attribute,  
> then the call
> +      // may store or load to the pointer, but it cannot escape.
> +      if (cast<InvokeInst>(I)->paramHasAttr(UI.getOperandNo()-2,
> +                                            Attribute::NoCapture))
> +        continue;
> +      return true;
>     default:
>       return true;
>     }
>
> Added: llvm/trunk/test/Analysis/BasicAA/nocapture.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/BasicAA/nocapture.ll?rev=61239&view=auto
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/test/Analysis/BasicAA/nocapture.ll (added)
> +++ llvm/trunk/test/Analysis/BasicAA/nocapture.ll Fri Dec 19  
> 00:39:12 2008
> @@ -0,0 +1,14 @@
> +; RUN: llvm-as < %s | opt -basicaa -gvn -instcombine | llvm-dis |  
> grep {ret i32 0}
> +
> +declare i32* @test(i32* nocapture)
> +
> +define i32 @test2() {
> +       %P = alloca i32
> +       %Q = call i32* @test(i32* %P)
> +       %a = load i32* %P
> +       store i32 4, i32* %Q   ;; cannot clobber P since it is  
> nocapture.
> +       %b = load i32* %P
> +       %c = sub i32 %a, %b
> +       ret i32 %c
> +}
> +
>
>
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