[llvm] r247958 - [ShrinkWrap] Refactor the handling of infinite loop in the analysis.
Quentin Colombet via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 17 16:21:35 PDT 2015
Author: qcolombet
Date: Thu Sep 17 18:21:34 2015
New Revision: 247958
URL: http://llvm.org/viewvc/llvm-project?rev=247958&view=rev
Log:
[ShrinkWrap] Refactor the handling of infinite loop in the analysis.
- Strenghten the logic to be sure we hoist the restore point out of the current
loop. (The fixes a bug with infinite loop, added as part of the patch.)
- Walk over the exit blocks of the current loop to conver to the desired restore
point in one iteration of the update loop.
Modified:
llvm/trunk/lib/CodeGen/ShrinkWrap.cpp
llvm/trunk/test/CodeGen/AArch64/arm64-shrink-wrapping.ll
llvm/trunk/test/CodeGen/ARM/arm-shrink-wrapping.ll
llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll
llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll
Modified: llvm/trunk/lib/CodeGen/ShrinkWrap.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ShrinkWrap.cpp?rev=247958&r1=247957&r2=247958&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/ShrinkWrap.cpp (original)
+++ llvm/trunk/lib/CodeGen/ShrinkWrap.cpp Thu Sep 17 18:21:34 2015
@@ -313,16 +313,18 @@ void ShrinkWrap::updateSaveRestorePoints
// for a post-dominator outside the loop.
SmallVector<MachineBasicBlock*, 4> ExitBlocks;
MLI->getLoopFor(Restore)->getExitingBlocks(ExitBlocks);
- if (ExitBlocks.empty()) {
- Restore = nullptr;
- break;
+ // Push Restore outside of this loop.
+ // Look for the immediate post-dominator of the loop exits.
+ MachineBasicBlock *IPdom = Restore;
+ for (MachineBasicBlock *LoopExitBB: ExitBlocks) {
+ IPdom = FindIDom<>(*IPdom, LoopExitBB->successors(), *MPDT);
+ if (!IPdom)
+ break;
}
- // Push Restore outside of this loop if immediate post-dominator is
- // different from restore block. If immediate post-dominator is not
- // different, bail out.
- MachineBasicBlock *IPdom =
- FindIDom<>(*Restore, Restore->successors(), *MPDT);
- if (IPdom != Restore)
+ // If the immediate post-dominator is not in a less nested loop,
+ // then we are stuck in a program with an infinite loop.
+ // In that case, we will not find a safe point, hence, bail out.
+ if (IPdom && MLI->getLoopDepth(IPdom) < MLI->getLoopDepth(Restore))
Restore = IPdom;
else {
Restore = nullptr;
Modified: llvm/trunk/test/CodeGen/AArch64/arm64-shrink-wrapping.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/arm64-shrink-wrapping.ll?rev=247958&r1=247957&r2=247958&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/arm64-shrink-wrapping.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/arm64-shrink-wrapping.ll Thu Sep 17 18:21:34 2015
@@ -568,3 +568,65 @@ for.body:
if.end:
ret void
}
+
+; Another infinite loop test this time with a body bigger than just one block.
+; CHECK-LABEL: infiniteloop2
+; CHECK: ret
+define void @infiniteloop2() {
+entry:
+ br i1 undef, label %if.then, label %if.end
+
+if.then:
+ %ptr = alloca i32, i32 4
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %sum.03 = phi i32 [ 0, %if.then ], [ %add, %body1 ], [ 1, %body2]
+ %call = tail call i32 asm "mov $0, #0", "=r,~{x19}"()
+ %add = add nsw i32 %call, %sum.03
+ store i32 %add, i32* %ptr
+ br i1 undef, label %body1, label %body2
+
+body1:
+ tail call void asm sideeffect "nop", "~{x19}"()
+ br label %for.body
+
+body2:
+ tail call void asm sideeffect "nop", "~{x19}"()
+ br label %for.body
+
+if.end:
+ ret void
+}
+
+; Another infinite loop test this time with two nested infinite loop.
+; CHECK-LABEL: infiniteloop3
+; CHECK: ret
+define void @infiniteloop3() {
+entry:
+ br i1 undef, label %loop2a, label %body
+
+body: ; preds = %entry
+ br i1 undef, label %loop2a, label %end
+
+loop1: ; preds = %loop2a, %loop2b
+ %var.phi = phi i32* [ %next.phi, %loop2b ], [ %var, %loop2a ]
+ %next.phi = phi i32* [ %next.load, %loop2b ], [ %next.var, %loop2a ]
+ %0 = icmp eq i32* %var, null
+ %next.load = load i32*, i32** undef
+ br i1 %0, label %loop2a, label %loop2b
+
+loop2a: ; preds = %loop1, %body, %entry
+ %var = phi i32* [ null, %body ], [ null, %entry ], [ %next.phi, %loop1 ]
+ %next.var = phi i32* [ undef, %body ], [ null, %entry ], [ %next.load, %loop1 ]
+ br label %loop1
+
+loop2b: ; preds = %loop1
+ %gep1 = bitcast i32* %var.phi to i32*
+ %next.ptr = bitcast i32* %gep1 to i32**
+ store i32* %next.phi, i32** %next.ptr
+ br label %loop1
+
+end:
+ ret void
+}
Modified: llvm/trunk/test/CodeGen/ARM/arm-shrink-wrapping.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/arm-shrink-wrapping.ll?rev=247958&r1=247957&r2=247958&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/arm-shrink-wrapping.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/arm-shrink-wrapping.ll Thu Sep 17 18:21:34 2015
@@ -562,3 +562,65 @@ for.body:
if.end:
ret void
}
+
+; Another infinite loop test this time with a body bigger than just one block.
+; CHECK-LABEL: infiniteloop2
+; CHECK: pop
+define void @infiniteloop2() {
+entry:
+ br i1 undef, label %if.then, label %if.end
+
+if.then:
+ %ptr = alloca i32, i32 4
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %sum.03 = phi i32 [ 0, %if.then ], [ %add, %body1 ], [ 1, %body2]
+ %call = tail call i32 asm "mov $0, #0", "=r,~{r4}"()
+ %add = add nsw i32 %call, %sum.03
+ store i32 %add, i32* %ptr
+ br i1 undef, label %body1, label %body2
+
+body1:
+ tail call void asm sideeffect "nop", "~{r4}"()
+ br label %for.body
+
+body2:
+ tail call void asm sideeffect "nop", "~{r4}"()
+ br label %for.body
+
+if.end:
+ ret void
+}
+
+; Another infinite loop test this time with two nested infinite loop.
+; CHECK-LABEL: infiniteloop3
+; CHECK: bx lr
+define void @infiniteloop3() {
+entry:
+ br i1 undef, label %loop2a, label %body
+
+body: ; preds = %entry
+ br i1 undef, label %loop2a, label %end
+
+loop1: ; preds = %loop2a, %loop2b
+ %var.phi = phi i32* [ %next.phi, %loop2b ], [ %var, %loop2a ]
+ %next.phi = phi i32* [ %next.load, %loop2b ], [ %next.var, %loop2a ]
+ %0 = icmp eq i32* %var, null
+ %next.load = load i32*, i32** undef
+ br i1 %0, label %loop2a, label %loop2b
+
+loop2a: ; preds = %loop1, %body, %entry
+ %var = phi i32* [ null, %body ], [ null, %entry ], [ %next.phi, %loop1 ]
+ %next.var = phi i32* [ undef, %body ], [ null, %entry ], [ %next.load, %loop1 ]
+ br label %loop1
+
+loop2b: ; preds = %loop1
+ %gep1 = bitcast i32* %var.phi to i32*
+ %next.ptr = bitcast i32* %gep1 to i32**
+ store i32* %next.phi, i32** %next.ptr
+ br label %loop1
+
+end:
+ ret void
+}
Modified: llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll?rev=247958&r1=247957&r2=247958&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll (original)
+++ llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll Thu Sep 17 18:21:34 2015
@@ -554,3 +554,65 @@ for.body:
if.end:
ret void
}
+
+; Another infinite loop test this time with a body bigger than just one block.
+; CHECK-LABEL: infiniteloop2
+; CHECK: blr
+define void @infiniteloop2() {
+entry:
+ br i1 undef, label %if.then, label %if.end
+
+if.then:
+ %ptr = alloca i32, i32 4
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %sum.03 = phi i32 [ 0, %if.then ], [ %add, %body1 ], [ 1, %body2]
+ %call = tail call i32 asm "mftb $0, 268", "=r,~{r14}"()
+ %add = add nsw i32 %call, %sum.03
+ store i32 %add, i32* %ptr
+ br i1 undef, label %body1, label %body2
+
+body1:
+ tail call void asm sideeffect "nop", "~{r14}"()
+ br label %for.body
+
+body2:
+ tail call void asm sideeffect "nop", "~{r14}"()
+ br label %for.body
+
+if.end:
+ ret void
+}
+
+; Another infinite loop test this time with two nested infinite loop.
+; CHECK-LABEL: infiniteloop3
+; CHECK: # %end
+define void @infiniteloop3() {
+entry:
+ br i1 undef, label %loop2a, label %body
+
+body: ; preds = %entry
+ br i1 undef, label %loop2a, label %end
+
+loop1: ; preds = %loop2a, %loop2b
+ %var.phi = phi i32* [ %next.phi, %loop2b ], [ %var, %loop2a ]
+ %next.phi = phi i32* [ %next.load, %loop2b ], [ %next.var, %loop2a ]
+ %0 = icmp eq i32* %var, null
+ %next.load = load i32*, i32** undef
+ br i1 %0, label %loop2a, label %loop2b
+
+loop2a: ; preds = %loop1, %body, %entry
+ %var = phi i32* [ null, %body ], [ null, %entry ], [ %next.phi, %loop1 ]
+ %next.var = phi i32* [ undef, %body ], [ null, %entry ], [ %next.load, %loop1 ]
+ br label %loop1
+
+loop2b: ; preds = %loop1
+ %gep1 = bitcast i32* %var.phi to i32*
+ %next.ptr = bitcast i32* %gep1 to i32**
+ store i32* %next.phi, i32** %next.ptr
+ br label %loop1
+
+end:
+ ret void
+}
Modified: llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll?rev=247958&r1=247957&r2=247958&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll (original)
+++ llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll Thu Sep 17 18:21:34 2015
@@ -697,3 +697,35 @@ body2:
if.end:
ret void
}
+
+; Another infinite loop test this time with two nested infinite loop.
+; CHECK-LABEL: infiniteloop3
+; CHECK: retq
+define void @infiniteloop3() {
+entry:
+ br i1 undef, label %loop2a, label %body
+
+body: ; preds = %entry
+ br i1 undef, label %loop2a, label %end
+
+loop1: ; preds = %loop2a, %loop2b
+ %var.phi = phi i32* [ %next.phi, %loop2b ], [ %var, %loop2a ]
+ %next.phi = phi i32* [ %next.load, %loop2b ], [ %next.var, %loop2a ]
+ %0 = icmp eq i32* %var, null
+ %next.load = load i32*, i32** undef
+ br i1 %0, label %loop2a, label %loop2b
+
+loop2a: ; preds = %loop1, %body, %entry
+ %var = phi i32* [ null, %body ], [ null, %entry ], [ %next.phi, %loop1 ]
+ %next.var = phi i32* [ undef, %body ], [ null, %entry ], [ %next.load, %loop1 ]
+ br label %loop1
+
+loop2b: ; preds = %loop1
+ %gep1 = bitcast i32* %var.phi to i32*
+ %next.ptr = bitcast i32* %gep1 to i32**
+ store i32* %next.phi, i32** %next.ptr
+ br label %loop1
+
+end:
+ ret void
+}
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