[PATCH] StructurizeCFG: Fix inverting a branch on an argument
Tom Stellard
tom at stellard.net
Thu Nov 21 16:26:54 PST 2013
On Thu, Nov 21, 2013 at 03:47:27PM -0800, Matt Arsenault wrote:
> Add a test case that doesn't have an infinite loop
Thanks, LGTM.
>
> http://llvm-reviews.chandlerc.com/D2196
>
> CHANGE SINCE LAST DIFF
> http://llvm-reviews.chandlerc.com/D2196?vs=5598&id=5724#toc
>
> Files:
> lib/Transforms/Scalar/StructurizeCFG.cpp
> test/Transforms/StructurizeCFG/branch-on-argument.ll
>
> Index: lib/Transforms/Scalar/StructurizeCFG.cpp
> ===================================================================
> --- lib/Transforms/Scalar/StructurizeCFG.cpp
> +++ lib/Transforms/Scalar/StructurizeCFG.cpp
> @@ -323,21 +323,32 @@
> if (match(Condition, m_Not(m_Value(Condition))))
> return Condition;
>
> - // Third: Check all the users for an invert
> - BasicBlock *Parent = cast<Instruction>(Condition)->getParent();
> - for (Value::use_iterator I = Condition->use_begin(),
> - E = Condition->use_end(); I != E; ++I) {
> + if (Instruction *Inst = dyn_cast<Instruction>(Condition)) {
> + // Third: Check all the users for an invert
> + BasicBlock *Parent = Inst->getParent();
> + for (Value::use_iterator I = Condition->use_begin(),
> + E = Condition->use_end(); I != E; ++I) {
> +
> + Instruction *User = dyn_cast<Instruction>(*I);
> + if (!User || User->getParent() != Parent)
> + continue;
>
> - Instruction *User = dyn_cast<Instruction>(*I);
> - if (!User || User->getParent() != Parent)
> - continue;
> + if (match(*I, m_Not(m_Specific(Condition))))
> + return *I;
> + }
> +
> + // Last option: Create a new instruction
> + return BinaryOperator::CreateNot(Condition, "", Parent->getTerminator());
> + }
>
> - if (match(*I, m_Not(m_Specific(Condition))))
> - return *I;
> + if (Argument *Arg = dyn_cast<Argument>(Condition)) {
> + BasicBlock &EntryBlock = Arg->getParent()->getEntryBlock();
> + return BinaryOperator::CreateNot(Condition,
> + Arg->getName() + ".inv",
> + EntryBlock.getTerminator());
> }
>
> - // Last option: Create a new instruction
> - return BinaryOperator::CreateNot(Condition, "", Parent->getTerminator());
> + llvm_unreachable("Unhandled condition to invert");
> }
>
> /// \brief Build the condition for one edge
> Index: test/Transforms/StructurizeCFG/branch-on-argument.ll
> ===================================================================
> --- /dev/null
> +++ test/Transforms/StructurizeCFG/branch-on-argument.ll
> @@ -0,0 +1,47 @@
> +; RUN: opt -S -o - -structurizecfg < %s | FileCheck %s
> +
> +; CHECK-LABEL: @invert_branch_on_arg_inf_loop(
> +; CHECK: entry:
> +; CHECK: %arg.inv = xor i1 %arg, true
> +; CHECK: phi i1 [ false, %Flow1 ], [ %arg.inv, %entry ]
> +define void @invert_branch_on_arg_inf_loop(i32 addrspace(1)* %out, i1 %arg) {
> +entry:
> + br i1 %arg, label %for.end, label %for.body
> +
> +for.body: ; preds = %entry, %for.body
> + store i32 999, i32 addrspace(1)* %out, align 4
> + br label %for.body
> +
> +for.end: ; preds = %Flow
> + ret void
> +}
> +
> +
> +; CHECK-LABEL: @invert_branch_on_arg_jump_into_loop(
> +; CHECK: entry:
> +; CHECK: %arg.inv = xor i1 %arg, true
> +; CHECK: Flow:
> +; CHECK: Flow1:
> +define void @invert_branch_on_arg_jump_into_loop(i32 addrspace(1)* %out, i32 %n, i1 %arg) {
> +entry:
> + br label %for.body
> +
> +for.body:
> + %i = phi i32 [0, %entry], [%i.inc, %end.loop]
> + %ptr = getelementptr i32 addrspace(1)* %out, i32 %i
> + store i32 %i, i32 addrspace(1)* %ptr, align 4
> + br i1 %arg, label %mid.loop, label %end.loop
> +
> +mid.loop:
> + store i32 333, i32 addrspace(1)* %out, align 4
> + br label %for.end
> +
> +end.loop:
> + %i.inc = add i32 %i, 1
> + %cmp = icmp ne i32 %i.inc, %n
> + br i1 %cmp, label %for.body, label %for.end
> +
> +for.end:
> + ret void
> +}
> +
> Index: lib/Transforms/Scalar/StructurizeCFG.cpp
> ===================================================================
> --- lib/Transforms/Scalar/StructurizeCFG.cpp
> +++ lib/Transforms/Scalar/StructurizeCFG.cpp
> @@ -323,21 +323,32 @@
> if (match(Condition, m_Not(m_Value(Condition))))
> return Condition;
>
> - // Third: Check all the users for an invert
> - BasicBlock *Parent = cast<Instruction>(Condition)->getParent();
> - for (Value::use_iterator I = Condition->use_begin(),
> - E = Condition->use_end(); I != E; ++I) {
> + if (Instruction *Inst = dyn_cast<Instruction>(Condition)) {
> + // Third: Check all the users for an invert
> + BasicBlock *Parent = Inst->getParent();
> + for (Value::use_iterator I = Condition->use_begin(),
> + E = Condition->use_end(); I != E; ++I) {
> +
> + Instruction *User = dyn_cast<Instruction>(*I);
> + if (!User || User->getParent() != Parent)
> + continue;
>
> - Instruction *User = dyn_cast<Instruction>(*I);
> - if (!User || User->getParent() != Parent)
> - continue;
> + if (match(*I, m_Not(m_Specific(Condition))))
> + return *I;
> + }
> +
> + // Last option: Create a new instruction
> + return BinaryOperator::CreateNot(Condition, "", Parent->getTerminator());
> + }
>
> - if (match(*I, m_Not(m_Specific(Condition))))
> - return *I;
> + if (Argument *Arg = dyn_cast<Argument>(Condition)) {
> + BasicBlock &EntryBlock = Arg->getParent()->getEntryBlock();
> + return BinaryOperator::CreateNot(Condition,
> + Arg->getName() + ".inv",
> + EntryBlock.getTerminator());
> }
>
> - // Last option: Create a new instruction
> - return BinaryOperator::CreateNot(Condition, "", Parent->getTerminator());
> + llvm_unreachable("Unhandled condition to invert");
> }
>
> /// \brief Build the condition for one edge
> Index: test/Transforms/StructurizeCFG/branch-on-argument.ll
> ===================================================================
> --- /dev/null
> +++ test/Transforms/StructurizeCFG/branch-on-argument.ll
> @@ -0,0 +1,47 @@
> +; RUN: opt -S -o - -structurizecfg < %s | FileCheck %s
> +
> +; CHECK-LABEL: @invert_branch_on_arg_inf_loop(
> +; CHECK: entry:
> +; CHECK: %arg.inv = xor i1 %arg, true
> +; CHECK: phi i1 [ false, %Flow1 ], [ %arg.inv, %entry ]
> +define void @invert_branch_on_arg_inf_loop(i32 addrspace(1)* %out, i1 %arg) {
> +entry:
> + br i1 %arg, label %for.end, label %for.body
> +
> +for.body: ; preds = %entry, %for.body
> + store i32 999, i32 addrspace(1)* %out, align 4
> + br label %for.body
> +
> +for.end: ; preds = %Flow
> + ret void
> +}
> +
> +
> +; CHECK-LABEL: @invert_branch_on_arg_jump_into_loop(
> +; CHECK: entry:
> +; CHECK: %arg.inv = xor i1 %arg, true
> +; CHECK: Flow:
> +; CHECK: Flow1:
> +define void @invert_branch_on_arg_jump_into_loop(i32 addrspace(1)* %out, i32 %n, i1 %arg) {
> +entry:
> + br label %for.body
> +
> +for.body:
> + %i = phi i32 [0, %entry], [%i.inc, %end.loop]
> + %ptr = getelementptr i32 addrspace(1)* %out, i32 %i
> + store i32 %i, i32 addrspace(1)* %ptr, align 4
> + br i1 %arg, label %mid.loop, label %end.loop
> +
> +mid.loop:
> + store i32 333, i32 addrspace(1)* %out, align 4
> + br label %for.end
> +
> +end.loop:
> + %i.inc = add i32 %i, 1
> + %cmp = icmp ne i32 %i.inc, %n
> + br i1 %cmp, label %for.body, label %for.end
> +
> +for.end:
> + ret void
> +}
> +
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