[llvm] r246331 - Revert r246232 and r246304.
David Majnemer via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 28 14:13:39 PDT 2015
Author: majnemer
Date: Fri Aug 28 16:13:39 2015
New Revision: 246331
URL: http://llvm.org/viewvc/llvm-project?rev=246331&view=rev
Log:
Revert r246232 and r246304.
This reverts isSafeToSpeculativelyExecute's use of ReadNone until we
split ReadNone into two pieces: one attribute which reasons about how
the function reasons about memory and another attribute which determines
how it may be speculated, CSE'd, trap, etc.
Modified:
llvm/trunk/lib/Analysis/ValueTracking.cpp
llvm/trunk/lib/CodeGen/Analysis.cpp
llvm/trunk/test/Transforms/SimplifyCFG/speculate-math.ll
Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=246331&r1=246330&r2=246331&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Fri Aug 28 16:13:39 2015
@@ -3147,11 +3147,46 @@ bool llvm::isSafeToSpeculativelyExecute(
LI->getPointerOperand(), LI->getAlignment(), DL, CtxI, DT, TLI);
}
case Instruction::Call: {
- auto *CI = cast<CallInst>(Inst);
- if (CI->doesNotAccessMemory() && !CI->isMustTailCall())
- return true;
+ if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
+ switch (II->getIntrinsicID()) {
+ // These synthetic intrinsics have no side-effects and just mark
+ // information about their operands.
+ // FIXME: There are other no-op synthetic instructions that potentially
+ // should be considered at least *safe* to speculate...
+ case Intrinsic::dbg_declare:
+ case Intrinsic::dbg_value:
+ return true;
+
+ case Intrinsic::bswap:
+ case Intrinsic::ctlz:
+ case Intrinsic::ctpop:
+ case Intrinsic::cttz:
+ case Intrinsic::objectsize:
+ case Intrinsic::sadd_with_overflow:
+ case Intrinsic::smul_with_overflow:
+ case Intrinsic::ssub_with_overflow:
+ case Intrinsic::uadd_with_overflow:
+ case Intrinsic::umul_with_overflow:
+ case Intrinsic::usub_with_overflow:
+ return true;
+ // Sqrt should be OK, since the llvm sqrt intrinsic isn't defined to set
+ // errno like libm sqrt would.
+ case Intrinsic::sqrt:
+ case Intrinsic::fma:
+ case Intrinsic::fmuladd:
+ case Intrinsic::fabs:
+ case Intrinsic::minnum:
+ case Intrinsic::maxnum:
+ return true;
+ // TODO: some fp intrinsics are marked as having the same error handling
+ // as libm. They're safe to speculate when they won't error.
+ // TODO: are convert_{from,to}_fp16 safe?
+ // TODO: can we list target-specific intrinsics here?
+ default: break;
+ }
+ }
return false; // The called function could have undefined behavior or
- // side-effects.
+ // side-effects, even if marked readnone nounwind.
}
case Instruction::VAArg:
case Instruction::Alloca:
Modified: llvm/trunk/lib/CodeGen/Analysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/Analysis.cpp?rev=246331&r1=246330&r2=246331&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/Analysis.cpp (original)
+++ llvm/trunk/lib/CodeGen/Analysis.cpp Fri Aug 28 16:13:39 2015
@@ -506,16 +506,18 @@ bool llvm::isInTailCallPosition(Immutabl
// If I will have a chain, make sure no other instruction that will have a
// chain interposes between I and the return.
- for (BasicBlock::const_iterator BBI = std::prev(ExitBB->end(), 2);; --BBI) {
- if (&*BBI == I)
- break;
- // Debug info intrinsics do not get in the way of tail call optimization.
- if (isa<DbgInfoIntrinsic>(BBI))
- continue;
- if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
- !isSafeToSpeculativelyExecute(BBI))
- return false;
- }
+ if (I->mayHaveSideEffects() || I->mayReadFromMemory() ||
+ !isSafeToSpeculativelyExecute(I))
+ for (BasicBlock::const_iterator BBI = std::prev(ExitBB->end(), 2);; --BBI) {
+ if (&*BBI == I)
+ break;
+ // Debug info intrinsics do not get in the way of tail call optimization.
+ if (isa<DbgInfoIntrinsic>(BBI))
+ continue;
+ if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
+ !isSafeToSpeculativelyExecute(BBI))
+ return false;
+ }
const Function *F = ExitBB->getParent();
return returnTypeIsEligibleForTailCall(
Modified: llvm/trunk/test/Transforms/SimplifyCFG/speculate-math.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/speculate-math.ll?rev=246331&r1=246330&r2=246331&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/speculate-math.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyCFG/speculate-math.ll Fri Aug 28 16:13:39 2015
@@ -6,7 +6,6 @@ declare float @llvm.fmuladd.f32(float, f
declare float @llvm.fabs.f32(float) nounwind readonly
declare float @llvm.minnum.f32(float, float) nounwind readonly
declare float @llvm.maxnum.f32(float, float) nounwind readonly
-declare float @llvm.copysign.f32(float, float) nounwind readonly
; CHECK-LABEL: @sqrt_test(
; CHECK: select
@@ -108,21 +107,4 @@ test_maxnum.exit:
%cond.i = phi float [ %0, %cond.else.i ], [ 0x7FF8000000000000, %entry ]
store float %cond.i, float addrspace(1)* %out, align 4
ret void
-}
-
-; CHECK-LABEL: @copysign_test(
-; CHECK: select
-define void @copysign_test(float addrspace(1)* noalias nocapture %out, float %a, float %b) nounwind {
-entry:
- %cmp.i = fcmp olt float %a, 0.000000e+00
- br i1 %cmp.i, label %test_copysign.exit, label %cond.else.i
-
-cond.else.i: ; preds = %entry
- %0 = tail call float @llvm.copysign.f32(float %a, float %b) nounwind readnone
- br label %test_copysign.exit
-
-test_copysign.exit: ; preds = %cond.else.i, %entry
- %cond.i = phi float [ %0, %cond.else.i ], [ 0x7FF8000000000000, %entry ]
- store float %cond.i, float addrspace(1)* %out, align 4
- ret void
}
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