[llvm] r337936 - Fix llvm::ComputeNumSignBits with some operations and llvm.assume
Stanislav Mekhanoshin via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 25 09:39:24 PDT 2018
Author: rampitec
Date: Wed Jul 25 09:39:24 2018
New Revision: 337936
URL: http://llvm.org/viewvc/llvm-project?rev=337936&view=rev
Log:
Fix llvm::ComputeNumSignBits with some operations and llvm.assume
Currently ComputeNumSignBits does early exit while processing some
of the operations (add, sub, mul, and select). This prevents the
function from using AssumptionCacheTracker if passed.
Differential Revision: https://reviews.llvm.org/D49759
Added:
llvm/trunk/test/Analysis/ValueTracking/numsignbits-from-assume.ll
Modified:
llvm/trunk/lib/Analysis/ValueTracking.cpp
Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=337936&r1=337935&r2=337936&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Wed Jul 25 09:39:24 2018
@@ -2337,7 +2337,7 @@ static unsigned ComputeNumSignBitsImpl(c
case Instruction::Select:
Tmp = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
- if (Tmp == 1) return 1; // Early out.
+ if (Tmp == 1) break;
Tmp2 = ComputeNumSignBits(U->getOperand(2), Depth + 1, Q);
return std::min(Tmp, Tmp2);
@@ -2345,7 +2345,7 @@ static unsigned ComputeNumSignBitsImpl(c
// Add can have at most one carry bit. Thus we know that the output
// is, at worst, one more bit than the inputs.
Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
- if (Tmp == 1) return 1; // Early out.
+ if (Tmp == 1) break;
// Special case decrementing a value (ADD X, -1):
if (const auto *CRHS = dyn_cast<Constant>(U->getOperand(1)))
@@ -2365,12 +2365,12 @@ static unsigned ComputeNumSignBitsImpl(c
}
Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
- if (Tmp2 == 1) return 1;
+ if (Tmp2 == 1) break;
return std::min(Tmp, Tmp2)-1;
case Instruction::Sub:
Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
- if (Tmp2 == 1) return 1;
+ if (Tmp2 == 1) break;
// Handle NEG.
if (const auto *CLHS = dyn_cast<Constant>(U->getOperand(0)))
@@ -2393,15 +2393,15 @@ static unsigned ComputeNumSignBitsImpl(c
// Sub can have at most one carry bit. Thus we know that the output
// is, at worst, one more bit than the inputs.
Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
- if (Tmp == 1) return 1; // Early out.
+ if (Tmp == 1) break;
return std::min(Tmp, Tmp2)-1;
case Instruction::Mul: {
// The output of the Mul can be at most twice the valid bits in the inputs.
unsigned SignBitsOp0 = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
- if (SignBitsOp0 == 1) return 1; // Early out.
+ if (SignBitsOp0 == 1) break;
unsigned SignBitsOp1 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
- if (SignBitsOp1 == 1) return 1;
+ if (SignBitsOp1 == 1) break;
unsigned OutValidBits =
(TyBits - SignBitsOp0 + 1) + (TyBits - SignBitsOp1 + 1);
return OutValidBits > TyBits ? 1 : TyBits - OutValidBits + 1;
Added: llvm/trunk/test/Analysis/ValueTracking/numsignbits-from-assume.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ValueTracking/numsignbits-from-assume.ll?rev=337936&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/ValueTracking/numsignbits-from-assume.ll (added)
+++ llvm/trunk/test/Analysis/ValueTracking/numsignbits-from-assume.ll Wed Jul 25 09:39:24 2018
@@ -0,0 +1,109 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define i32 @computeNumSignBits_add1(i32 %in) {
+; CHECK-LABEL: @computeNumSignBits_add1(
+; CHECK-NEXT: [[ADD:%.*]] = add i32 [[IN:%.*]], 1
+; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[ADD]], 43
+; CHECK-NEXT: call void @llvm.assume(i1 [[COND]])
+; CHECK-NEXT: [[SH:%.*]] = shl nuw nsw i32 [[ADD]], 3
+; CHECK-NEXT: ret i32 [[SH]]
+;
+ %add = add i32 %in, 1
+ %cond = icmp ule i32 %add, 42
+ call void @llvm.assume(i1 %cond)
+ %sh = shl i32 %add, 3
+ ret i32 %sh
+}
+
+define i32 @computeNumSignBits_add2(i32 %in1, i32 %in2) {
+; CHECK-LABEL: @computeNumSignBits_add2(
+; CHECK-NEXT: [[ADD:%.*]] = add i32 [[IN1:%.*]], [[IN2:%.*]]
+; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[ADD]], 43
+; CHECK-NEXT: call void @llvm.assume(i1 [[COND]])
+; CHECK-NEXT: [[SH:%.*]] = shl nuw nsw i32 [[ADD]], 3
+; CHECK-NEXT: ret i32 [[SH]]
+;
+ %add = add i32 %in1, %in2
+ %cond = icmp ule i32 %add, 42
+ call void @llvm.assume(i1 %cond)
+ %sh = shl i32 %add, 3
+ ret i32 %sh
+}
+
+define i32 @computeNumSignBits_sub1(i32 %in) {
+; CHECK-LABEL: @computeNumSignBits_sub1(
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 1, [[IN:%.*]]
+; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[SUB]], 43
+; CHECK-NEXT: call void @llvm.assume(i1 [[COND]])
+; CHECK-NEXT: [[SH:%.*]] = shl nuw nsw i32 [[SUB]], 3
+; CHECK-NEXT: ret i32 [[SH]]
+;
+ %sub = sub i32 1, %in
+ %cond = icmp ule i32 %sub, 42
+ call void @llvm.assume(i1 %cond)
+ %sh = shl i32 %sub, 3
+ ret i32 %sh
+}
+
+define i32 @computeNumSignBits_sub2(i32 %in) {
+; CHECK-LABEL: @computeNumSignBits_sub2(
+; CHECK-NEXT: [[SUB:%.*]] = add i32 [[IN:%.*]], -1
+; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[SUB]], 43
+; CHECK-NEXT: call void @llvm.assume(i1 [[COND]])
+; CHECK-NEXT: [[SH:%.*]] = shl nuw nsw i32 [[SUB]], 3
+; CHECK-NEXT: ret i32 [[SH]]
+;
+ %sub = sub i32 %in, 1
+ %cond = icmp ule i32 %sub, 42
+ call void @llvm.assume(i1 %cond)
+ %sh = shl i32 %sub, 3
+ ret i32 %sh
+}
+
+define i32 @computeNumSignBits_sub3(i32 %in1, i32 %in2) {
+; CHECK-LABEL: @computeNumSignBits_sub3(
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[IN1:%.*]], [[IN2:%.*]]
+; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[SUB]], 43
+; CHECK-NEXT: call void @llvm.assume(i1 [[COND]])
+; CHECK-NEXT: [[SH:%.*]] = shl nuw nsw i32 [[SUB]], 3
+; CHECK-NEXT: ret i32 [[SH]]
+;
+ %sub = sub i32 %in1, %in2
+ %cond = icmp ule i32 %sub, 42
+ call void @llvm.assume(i1 %cond)
+ %sh = shl i32 %sub, 3
+ ret i32 %sh
+}
+
+define i32 @computeNumSignBits_mul(i32 %in1, i32 %in2) {
+; CHECK-LABEL: @computeNumSignBits_mul(
+; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[IN1:%.*]], [[IN2:%.*]]
+; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[MUL]], 43
+; CHECK-NEXT: call void @llvm.assume(i1 [[COND]])
+; CHECK-NEXT: [[SH:%.*]] = shl nuw nsw i32 [[MUL]], 3
+; CHECK-NEXT: ret i32 [[SH]]
+;
+ %mul = mul i32 %in1, %in2
+ %cond = icmp ule i32 %mul, 42
+ call void @llvm.assume(i1 %cond)
+ %sh = shl i32 %mul, 3
+ ret i32 %sh
+}
+
+define i32 @computeNumSignBits_select(i32 %in, i1 %s) {
+; CHECK-LABEL: @computeNumSignBits_select(
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[S:%.*]], i32 [[IN:%.*]], i32 1
+; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[SEL]], 43
+; CHECK-NEXT: call void @llvm.assume(i1 [[COND]])
+; CHECK-NEXT: [[SH:%.*]] = shl nuw nsw i32 [[SEL]], 3
+; CHECK-NEXT: ret i32 [[SH]]
+;
+ %sel = select i1 %s, i32 %in, i32 1
+ %cond = icmp ule i32 %sel, 42
+ call void @llvm.assume(i1 %cond)
+ %sh = shl i32 %sel, 3
+ ret i32 %sh
+}
+
+declare void @llvm.assume(i1)
More information about the llvm-commits
mailing list