search for: indirectbrs

Hello, I have a question about the indirectbr instruction. I attempted to use it according to the example in the Assembly Language Reference manual, but got an "expected instruction opcode" error. Poking about on the web I found this document: http://nondot.org/sabre/LLVMNotes/IndirectGoto.txt which appears to be a Nov 2, 2009 proposal to add indirectbr and blockaddress() to the IR

Hi, I encountered an error while trying to use the indirectbr instruction with Alpha backend (current build). Here's part of the code sequence that I tried to compile: bb1: %1 = load i32* %i, align 4 %2 = add nsw i32 %1, 1 store i32 %2, i32* %i, align 4 indirectbr i8* blockaddress(@main, %bb1), [ label %bb1 ] br label %return This compiles correctly when I use the X86 or PPC

Hi, How does the requirement that phi instructions have one value per predecessor basic block interact with indirectbr instructions? For instance, take the following code: L1: br i1 %somevalue, label %L2, label %L3 L2: %ret1 = i8* blockaddress(@myfunction, %L5) br label %L4 L3: %ret2 = i8* blockaddress(@myfunction, %L6) br label %L4 L4: %ret = phi i8* [%ret1, L2], [%ret2, L3]

In my llvm jit project I needed to lookup BB addresses at execution time and then jump to the corresponding BB. A C++ routine called at runtime from IR finds the right BB, gets its BlockAddress and returns it as an i8*. The IR does an indirectbr on this value... Well, not really. The routine returns the address of a BlockAddress node. Is there any way to get the real runtime code address for the

Hi according to [1] and [2] the blockaddress of any basic block can be obtained. But I am not sure about that fact that an indirectbr can only target at a basic block which is within the same function as the indirectbr instruction. [1] states: ---8<--- All possible destination blocks must be listed in the label list, otherwise this instruction has undefined behavior. This implies that jumps

On Sat, Dec 11, 2010 at 4:19 PM, Maurice Marks <maurice.marks at gmail.com> wrote: > In my llvm jit project I needed to lookup BB addresses at execution time and > then jump to the corresponding BB. A C++ routine called at runtime from IR > finds the right BB, gets its BlockAddress and returns it as an i8*. The IR > does an indirectbr on this value... > Well, not really. The

On Jan 2, 2010, at 11:03 AM, Dustin Laurence wrote: > Hello, > > I have a question about the indirectbr instruction. I attempted to > use > it according to the example in the Assembly Language Reference manual, > but got an "expected instruction opcode" error. Poking about on the > web > I found this document: > >

Hello, I have a question about the indirectbr instruction. I attempted to use it according to the example in the Assembly Language Reference manual, but got an "expected instruction opcode" error. Poking about on the web I found this document: http://nondot.org/sabre/LLVMNotes/IndirectGoto.txt which appears to be a Nov 2, 2009 proposal to add indirectbr and blockaddress() to the IR

Consider this IR fragment produced after -O3: > %7: > %8 = phi i8* [ blockaddress(@0, %19), %19 ], [ %12, %11 ] > %9 = phi i32 [ %20, %19 ], [ 0, %11 ] > indirectbr i8* %8, [label %4, label %19] > > %19: > %20 = add nsw i32 %9, 1 > %21 = icmp eq i32 %9, 9999 > br i1 %21, label %16, label %7 the br in %19 should be optimized to branch directly to itself rather than going

On Jul 7, 2011, at 10:15 PM, Carlo Alberto Ferraris wrote: > Nella citazione giovedì 7 luglio 2011 19:41:16, John McCall ha scritto: >> On Jul 7, 2011, at 4:33 AM, Carlo Alberto Ferraris wrote: >>> Il 07/07/2011 11:14, Cameron Zwarich ha scritto: >>>> I haven't read the code in detail, but it looks like JumpThreading at least attempts to thread across indirect

Nella citazione giovedì 7 luglio 2011 19:41:16, John McCall ha scritto: > On Jul 7, 2011, at 4:33 AM, Carlo Alberto Ferraris wrote: >> Il 07/07/2011 11:14, Cameron Zwarich ha scritto: >>> I haven't read the code in detail, but it looks like JumpThreading at >>> least attempts to thread across indirect branches. You can either try >>> to fix it or file a

Hi, i ran into a problem when using blockaddress() with a label in another function. It seems to me that LLVM tries to remove the label used in blockaddress because it seems like it is not used, but in fact it may be used somewhere with a indirectbr. I attached a small test-case that produces this error. (The original problem is much more complicated, so i hope the reduced example, which has no

On Mar 15, 2010, at 7:11 AM, Sebastian Schlunke wrote: > Hi, > > i ran into a problem when using blockaddress() with a label in another function. It seems to me that LLVM tries to remove the label used in blockaddress because it seems like it is not used, but in fact it may be used somewhere with a indirectbr. > > I attached a small test-case that produces this error. (The

On Jul 7, 2011, at 2:05 AM, Carlo Alberto Ferraris wrote: > Consider this IR fragment produced after -O3: >> %7: >> %8 = phi i8* [ blockaddress(@0, %19), %19 ], [ %12, %11 ] >> %9 = phi i32 [ %20, %19 ], [ 0, %11 ] >> indirectbr i8* %8, [label %4, label %19] >> >> %19: >> %20 = add nsw i32 %9, 1 >> %21 = icmp eq i32 %9, 9999 >> br i1 %21,

On Jul 7, 2011, at 4:33 AM, Carlo Alberto Ferraris wrote: > Il 07/07/2011 11:14, Cameron Zwarich ha scritto: >> >> I haven't read the code in detail, but it looks like JumpThreading at least attempts to thread across indirect branches. You can either try to fix it or file a bug with your test case. > In the source it says "If the predecessor is an indirect goto, we

I see. But the block does not necessarily contain dead code. My original problem is more like this: define i32 @main() { entry: %target = bitcast i8* blockaddress(@test_fun, %test_label) to i8* call i32 @test_fun(i8* %target) ret i32 0 } define i32 @test_fun(i8* %target) { entry: indirectbr i8* %target, [label %test_label] test_label: ; assume some code here... br label %ret ret: ret

Il 07/07/2011 11:14, Cameron Zwarich ha scritto: > I haven't read the code in detail, but it looks like JumpThreading at > least attempts to thread across indirect branches. You can either try > to fix it or file a bug with your test case. In the source it says "If the predecessor is an indirect goto, we can't split the edge.

On Mar 15, 2010, at 9:41 AM, Chris Lattner wrote: > > On Mar 15, 2010, at 7:11 AM, Sebastian Schlunke wrote: > >> Hi, >> >> i ran into a problem when using blockaddress() with a label in another function. It seems to me that LLVM tries to remove the label used in blockaddress because it seems like it is not used, but in fact it may be used somewhere with a

Hi, The 'br' instruction has the syntax: br i1 <cond>, label <iftrue>, label <iffalse> br label <dest> ; Unconditional branch If we know <cond>'s type must be 'i1', <iftrue><iffalse><dest> have to be of type 'label', why does the syntax have to specify them?

On Jul 7, 2011, at 10:15 PM, Carlo Alberto Ferraris wrote: > I'll try to inspect the assembler. Just a quick thought in the mean time, in the snippet I posted, if the backedge pointed directly to %19, other optimizations would likely notice that the loop could be removed entirely and replaced with a single addition. Do you think the code generator is able t > o do this? Why would you