[llvm] 4a58996 - [SCCP] Use constant ranges for PHI nodes.
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 19 05:46:22 PDT 2020
Author: Florian Hahn
Date: 2020-03-19T12:45:33Z
New Revision: 4a58996dd2d226063bc9703c4722e06a5d041b23
URL: https://github.com/llvm/llvm-project/commit/4a58996dd2d226063bc9703c4722e06a5d041b23
DIFF: https://github.com/llvm/llvm-project/commit/4a58996dd2d226063bc9703c4722e06a5d041b23.diff
LOG: [SCCP] Use constant ranges for PHI nodes.
For PHIs with multiple incoming values, we can improve precision by
using constant ranges for integers. We can over-approximate phis
by merging the incoming values.
Reviewers: davide, efriedma, mssimpso
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D71933
Added:
llvm/test/Transforms/SCCP/ip-ranges-phis.ll
llvm/test/Transforms/SCCP/phis.ll
Modified:
llvm/lib/Transforms/Scalar/SCCP.cpp
llvm/test/Transforms/SCCP/binaryops-range-special-cases.ll
llvm/test/Transforms/SCCP/ip-constant-ranges.ll
llvm/test/Transforms/SCCP/range-and.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index 5df422e8e4b5..fcd7ed195291 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -739,9 +739,8 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
if (PN.getType()->isStructTy())
return (void)markOverdefined(&PN);
- if (isOverdefined(getValueState(&PN))) {
- return (void)markOverdefined(&PN);
- }
+ if (getValueState(&PN).isOverdefined())
+ return; // Quick exit
// Super-extra-high-degree PHI nodes are unlikely to ever be marked constant,
// and slow us down a lot. Just mark them overdefined.
@@ -753,38 +752,19 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
// constant, and they agree with each other, the PHI becomes the identical
// constant. If they are constant and don't agree, the PHI is overdefined.
// If there are no executable operands, the PHI remains unknown.
- Constant *OperandVal = nullptr;
+ bool Changed = false;
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
LatticeVal IV = getValueState(PN.getIncomingValue(i));
- if (IV.isUnknownOrUndef()) continue; // Doesn't influence PHI node.
-
if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent()))
continue;
- if (isOverdefined(IV)) // PHI node becomes overdefined!
- return (void)markOverdefined(&PN);
-
- if (!OperandVal) { // Grab the first value.
- OperandVal = getConstant(IV);
- continue;
- }
-
- // There is already a reachable operand. If we conflict with it,
- // then the PHI node becomes overdefined. If we agree with it, we
- // can continue on.
-
- // Check to see if there are two
diff erent constants merging, if so, the PHI
- // node is overdefined.
- if (getConstant(IV) != OperandVal)
- return (void)markOverdefined(&PN);
+ LatticeVal &Res = getValueState(&PN);
+ Changed |= Res.mergeIn(IV, DL);
+ if (Res.isOverdefined())
+ break;
}
-
- // If we exited the loop, this means that the PHI node only has constant
- // arguments that agree with each other(and OperandVal is the constant) or
- // OperandVal is null because there are no defined incoming arguments. If
- // this is the case, the PHI remains unknown.
- if (OperandVal)
- markConstant(&PN, OperandVal); // Acquire operand value
+ if (Changed)
+ pushToWorkListMsg(ValueState[&PN], &PN);
}
void SCCPSolver::visitReturnInst(ReturnInst &I) {
diff --git a/llvm/test/Transforms/SCCP/binaryops-range-special-cases.ll b/llvm/test/Transforms/SCCP/binaryops-range-special-cases.ll
index f2b036f982b8..f7fdc1ed5e64 100644
--- a/llvm/test/Transforms/SCCP/binaryops-range-special-cases.ll
+++ b/llvm/test/Transforms/SCCP/binaryops-range-special-cases.ll
@@ -44,8 +44,7 @@ define void @sdiv1_cmp_range_1(i32 %x, i1 %c) {
; CHECK: bb3:
; CHECK-NEXT: [[P:%.*]] = phi i32 [ 1, [[BB1]] ], [ 2, [[BB2]] ]
; CHECK-NEXT: [[D:%.*]] = sdiv i32 1, [[X:%.*]]
-; CHECK-NEXT: [[C_0:%.*]] = icmp slt i32 [[P]], [[D]]
-; CHECK-NEXT: call void @use(i1 [[C_0]])
+; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: [[C_1:%.*]] = icmp eq i32 [[P]], [[D]]
; CHECK-NEXT: call void @use(i1 [[C_1]])
; CHECK-NEXT: ret void
@@ -77,10 +76,8 @@ define void @sdiv1_cmp_range_2(i32 %x, i1 %c) {
; CHECK: bb3:
; CHECK-NEXT: [[P:%.*]] = phi i32 [ 3, [[BB1]] ], [ 2, [[BB2]] ]
; CHECK-NEXT: [[D:%.*]] = sdiv i32 1, [[X:%.*]]
-; CHECK-NEXT: [[C_0:%.*]] = icmp slt i32 [[P]], [[D]]
-; CHECK-NEXT: call void @use(i1 [[C_0]])
-; CHECK-NEXT: [[C_1:%.*]] = icmp eq i32 [[P]], [[D]]
-; CHECK-NEXT: call void @use(i1 [[C_1]])
+; CHECK-NEXT: call void @use(i1 false)
+; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: ret void
;
br i1 %c, label %bb1, label %bb2
diff --git a/llvm/test/Transforms/SCCP/ip-constant-ranges.ll b/llvm/test/Transforms/SCCP/ip-constant-ranges.ll
index dbaedaa739bf..891bebf105b8 100644
--- a/llvm/test/Transforms/SCCP/ip-constant-ranges.ll
+++ b/llvm/test/Transforms/SCCP/ip-constant-ranges.ll
@@ -59,12 +59,9 @@ entry:
ret i32 %res.2
}
-; x is overdefined, because constant ranges are only used for parameter
-; values.
; CHECK-LABEL: f3
-; CHECK: %cmp = icmp sgt i32 %x, 300
-; CHECK: %res = select i1 %cmp, i32 1, i32 2
-; CHECK: ret i32 %res
+; CHECK-LABEL: entry:
+; CHECK: ret i32 undef
define internal i32 @f3(i32 %x) {
entry:
%cmp = icmp sgt i32 %x, 300
@@ -83,7 +80,7 @@ if.true:
end:
%res = phi i32 [ 0, %entry], [ 1, %if.true ]
%call1 = tail call i32 @f3(i32 %res)
- ret i32 %call1
+ ret i32 2
}
; CHECK-LABEL: f4
diff --git a/llvm/test/Transforms/SCCP/ip-ranges-phis.ll b/llvm/test/Transforms/SCCP/ip-ranges-phis.ll
new file mode 100644
index 000000000000..a4a59d9c0f81
--- /dev/null
+++ b/llvm/test/Transforms/SCCP/ip-ranges-phis.ll
@@ -0,0 +1,215 @@
+; RUN: opt < %s -ipsccp -S | FileCheck %s
+
+define internal i32 @f1(i32 %x) {
+; CHECK-LABEL: define internal i32 @f1(
+; CHECK-NEXT: ret i32 undef
+;
+ %cmp = icmp sgt i32 %x, 300
+ %res = select i1 %cmp, i32 1, i32 2
+ ret i32 %res
+}
+
+; %res is a constant range [0, 2) from a PHI node.
+define i32 @caller1(i1 %cmp) {
+; CHECK-LABEL: define i32 @caller1(
+; CHECK-LABEL: entry:
+; CHECK-NEXT: br i1 %cmp, label %if.true, label %end
+
+; CHECK-LABEL: if.true:
+; CHECK-NEXT: br label %end
+
+; CHECK-LABEL: end:
+; CHECK-NEXT: %res = phi i32 [ 0, %entry ], [ 1, %if.true ]
+; CHECK-NEXT: %call1 = tail call i32 @f1(i32 %res)
+; CHECK-NEXT: ret i32 2
+;
+entry:
+ br i1 %cmp, label %if.true, label %end
+
+if.true:
+ br label %end
+
+end:
+ %res = phi i32 [ 0, %entry], [ 1, %if.true ]
+ %call1 = tail call i32 @f1(i32 %res)
+ ret i32 %call1
+}
+
+define internal i32 @f2(i32 %x, i32 %y, i32 %z, i1 %cmp.1, i1 %cmp.2) {
+; CHECK-LABEL: define internal i32 @f2(
+; CHECK-LABEL: entry:
+; CHECK-NEXT: br i1 %cmp.1, label %if.true.1, label %end
+
+; CHECK-LABEL: if.true.1:
+; CHECK-NEXT: br i1 %cmp.2, label %if.true.2, label %end
+
+; CHECK-LABEL: if.true.2:
+; CHECK-NEXT: br label %end
+
+; CHECK-LABEL: end:
+; CHECK-NEXT: %p = phi i32 [ %x, %entry ], [ %y, %if.true.1 ], [ %z, %if.true.2 ]
+; CHECK-NEXT: %c.1 = icmp sgt i32 %p, 5
+; CHECK-NEXT: %c.2 = icmp eq i32 %p, 0
+; CHECK-NEXT: %c.3 = icmp slt i32 %p, 0
+; CHECK-NEXT: %v.1 = select i1 %c.1, i32 10, i32 100
+; CHECK-NEXT: %v.2 = select i1 %c.2, i32 20, i32 200
+; CHECK-NEXT: %v.3 = select i1 %c.3, i32 30, i32 300
+; CHECK-NEXT: %r.1 = add i32 %v.1, %v.2
+; CHECK-NEXT: %r.2 = add i32 %r.1, %v.3
+; CHECK-NEXT: %r.3 = add i32 %r.2, 400
+; CHECK-NEXT: %r.4 = add i32 %r.3, 50
+; CHECK-NEXT: %r.5 = add i32 %r.4, 60
+; CHECK-NEXT: %r.6 = add i32 %r.4, 700
+; CHECK-NEXT: ret i32 %r.6
+;
+entry:
+ br i1 %cmp.1, label %if.true.1, label %end
+
+if.true.1:
+ br i1 %cmp.2, label %if.true.2, label %end
+
+if.true.2:
+ br label %end
+
+end:
+ %p = phi i32 [ %x, %entry ], [ %y, %if.true.1 ], [ %z, %if.true.2 ]
+ %c.1 = icmp sgt i32 %p, 5
+ %c.2 = icmp eq i32 %p, 0
+ %c.3 = icmp slt i32 %p, 0
+ %c.4 = icmp sgt i32 %p, 10
+ %c.5 = icmp sle i32 %p, 10
+ %c.6 = icmp sgt i32 %p, -11
+ %c.7 = icmp slt i32 %p, -11
+ %v.1 = select i1 %c.1, i32 10, i32 100
+ %v.2 = select i1 %c.2, i32 20, i32 200
+ %v.3 = select i1 %c.3, i32 30, i32 300
+ %v.4 = select i1 %c.4, i32 40, i32 400
+ %v.5 = select i1 %c.5, i32 50, i32 500
+ %v.6 = select i1 %c.6, i32 60, i32 600
+ %v.7 = select i1 %c.7, i32 70, i32 700
+ %r.1 = add i32 %v.1, %v.2
+ %r.2 = add i32 %r.1, %v.3
+ %r.3 = add i32 %r.2, %v.4
+ %r.4 = add i32 %r.3, %v.5
+ %r.5 = add i32 %r.4, %v.6
+ %r.6 = add i32 %r.4, %v.7
+ ret i32 %r.6
+}
+
+define i32 @caller2(i1 %cmp.1, i1 %cmp.2) {
+; CHECK-LABEL: define i32 @caller2(i1 %cmp.1, i1 %cmp.2) {
+; CHECK-LABEL: entry:
+; CHECK-NEXT: br i1 %cmp.1, label %if.true, label %end
+
+; CHECK-LABEL: if.true: ; preds = %entry
+; CHECK-NEXT: br label %end
+
+; CHECK-LABEL: end: ; preds = %if.true, %entry
+; CHECK-NEXT: %p1 = phi i32 [ 0, %entry ], [ 1, %if.true ]
+; CHECK-NEXT: %p2 = phi i32 [ 1, %entry ], [ -10, %if.true ]
+; CHECK-NEXT: %p3 = phi i32 [ 1, %entry ], [ 10, %if.true ]
+; CHECK-NEXT: %call1 = tail call i32 @f2(i32 %p1, i32 %p2, i32 %p3, i1 %cmp.1, i1 %cmp.2)
+; CHECK-NEXT: ret i32 %call1
+;
+
+entry:
+ br i1 %cmp.1, label %if.true, label %end
+
+if.true:
+ br label %end
+
+end:
+ %p1 = phi i32 [ 0, %entry], [ 1, %if.true ]
+ %p2 = phi i32 [ 1, %entry], [ -10, %if.true ]
+ %p3 = phi i32 [ 1, %entry], [ 10, %if.true ]
+ %call1 = tail call i32 @f2(i32 %p1, i32 %p2, i32 %p3, i1 %cmp.1, i1 %cmp.2)
+ ret i32 %call1
+}
+
+define internal i32 @f3(i32 %x, i32 %y, i1 %cmp.1) {
+; CHECK-LABEL: define internal i32 @f3(i32 %x, i32 %y, i1 %cmp.1) {
+; CHECK-LABEL: entry:
+; CHECK-NEXT: br i1 %cmp.1, label %if.true.1, label %end
+
+; CHECK-LABEL: if.true.1: ; preds = %entry
+; CHECK-NEXT: br label %end
+
+; CHECK-LABEL: end: ; preds = %if.true.1, %entry
+; CHECK-NEXT: %p = phi i32 [ %x, %entry ], [ %y, %if.true.1 ]
+; CHECK-NEXT: %c.1 = icmp sgt i32 %p, 5
+; CHECK-NEXT: %c.2 = icmp eq i32 %p, 0
+; CHECK-NEXT: %c.3 = icmp slt i32 %p, 0
+; CHECK-NEXT: %c.4 = icmp sgt i32 %p, 10
+; CHECK-NEXT: %c.5 = icmp sle i32 %p, 10
+; CHECK-NEXT: %c.6 = icmp sgt i32 %p, -11
+; CHECK-NEXT: %c.7 = icmp slt i32 %p, -11
+; CHECK-NEXT: %v.1 = select i1 %c.1, i32 10, i32 100
+; CHECK-NEXT: %v.2 = select i1 %c.2, i32 20, i32 200
+; CHECK-NEXT: %v.3 = select i1 %c.3, i32 30, i32 300
+; CHECK-NEXT: %v.4 = select i1 %c.4, i32 40, i32 400
+; CHECK-NEXT: %v.5 = select i1 %c.5, i32 50, i32 500
+; CHECK-NEXT: %v.6 = select i1 %c.6, i32 60, i32 600
+; CHECK-NEXT: %v.7 = select i1 %c.7, i32 70, i32 700
+; CHECK-NEXT: %r.1 = add i32 %v.1, %v.2
+; CHECK-NEXT: %r.2 = add i32 %r.1, %v.3
+; CHECK-NEXT: %r.3 = add i32 %r.2, %v.4
+; CHECK-NEXT: %r.4 = add i32 %r.3, %v.5
+; CHECK-NEXT: %r.5 = add i32 %r.4, %v.6
+; CHECK-NEXT: %r.6 = add i32 %r.4, %v.7
+; CHECK-NEXT: ret i32 %r.6
+;
+entry:
+ br i1 %cmp.1, label %if.true.1, label %end
+
+if.true.1:
+ br label %end
+
+end:
+ %p = phi i32 [ %x, %entry ], [ %y, %if.true.1 ]
+ %c.1 = icmp sgt i32 %p, 5
+ %c.2 = icmp eq i32 %p, 0
+ %c.3 = icmp slt i32 %p, 0
+ %c.4 = icmp sgt i32 %p, 10
+ %c.5 = icmp sle i32 %p, 10
+ %c.6 = icmp sgt i32 %p, -11
+ %c.7 = icmp slt i32 %p, -11
+ %v.1 = select i1 %c.1, i32 10, i32 100
+ %v.2 = select i1 %c.2, i32 20, i32 200
+ %v.3 = select i1 %c.3, i32 30, i32 300
+ %v.4 = select i1 %c.4, i32 40, i32 400
+ %v.5 = select i1 %c.5, i32 50, i32 500
+ %v.6 = select i1 %c.6, i32 60, i32 600
+ %v.7 = select i1 %c.7, i32 70, i32 700
+ %r.1 = add i32 %v.1, %v.2
+ %r.2 = add i32 %r.1, %v.3
+ %r.3 = add i32 %r.2, %v.4
+ %r.4 = add i32 %r.3, %v.5
+ %r.5 = add i32 %r.4, %v.6
+ %r.6 = add i32 %r.4, %v.7
+ ret i32 %r.6
+}
+
+define i32 @caller3(i32 %y, i1 %cmp.1) {
+; CHECK-LABEL: define i32 @caller3(i32 %y, i1 %cmp.1) {
+; CHECK-LABEL: entry:
+; CHECK-NEXT: br i1 %cmp.1, label %if.true, label %end
+
+; CHECK-LABEL: if.true:
+; CHECK-NEXT: br label %end
+
+; CHECK-LABEL: end:
+; CHECK-NEXT: %p1 = phi i32 [ 0, %entry ], [ 5, %if.true ]
+; CHECK-NEXT: %call1 = tail call i32 @f3(i32 %p1, i32 %y, i1 %cmp.1)
+; CHECK-NEXT: ret i32 %call1
+;
+entry:
+ br i1 %cmp.1, label %if.true, label %end
+
+if.true:
+ br label %end
+
+end:
+ %p1 = phi i32 [ 0, %entry], [ 5, %if.true ]
+ %call1 = tail call i32 @f3(i32 %p1, i32 %y, i1 %cmp.1)
+ ret i32 %call1
+}
diff --git a/llvm/test/Transforms/SCCP/phis.ll b/llvm/test/Transforms/SCCP/phis.ll
new file mode 100644
index 000000000000..dac8273ab2d1
--- /dev/null
+++ b/llvm/test/Transforms/SCCP/phis.ll
@@ -0,0 +1,81 @@
+; RUN: opt < %s -sccp -S | FileCheck %s
+
+define i1 @float.1(i1 %cmp) {
+; CHECK-LABEL: define i1 @float.1(i1 %cmp) {
+
+; CHECK-LABEL: end:
+; CHECK-NEXT: ret i1 true
+;
+entry:
+ br i1 %cmp, label %if.true, label %end
+
+if.true:
+ br label %end
+
+end:
+ %p = phi float [ 1.0, %entry ], [ 1.0, %if.true]
+ %c = fcmp ueq float %p, 1.0
+ ret i1 %c
+}
+
+define i1 @float.2(i1 %cmp) {
+; CHECK-LABEL: define i1 @float.2(i1 %cmp) {
+
+; CHECK-LABEL: end:
+; CHECK-NEXT: %p = phi float [ 1.000000e+00, %entry ], [ 2.000000e+00, %if.true ]
+; CHECK-NEXT: %c = fcmp ueq float %p, 1.000000e+00
+; CHECK-NEXT: ret i1 %c
+;
+entry:
+ br i1 %cmp, label %if.true, label %end
+
+if.true:
+ br label %end
+
+end:
+ %p = phi float [ 1.0, %entry ], [ 2.0, %if.true]
+ %c = fcmp ueq float %p, 1.0
+ ret i1 %c
+}
+
+define i1 @float.3(float %f, i1 %cmp) {
+; CHECK-LABEL: define i1 @float.3(float %f, i1 %cmp)
+
+; CHECK-LABEL: end:
+; CHECK-NEXT: %p = phi float [ 1.000000e+00, %entry ], [ %f, %if.true ]
+; CHECK-NEXT: %c = fcmp ueq float %p, 1.000000e+00
+; CHECK-NEXT: ret i1 %c
+;
+entry:
+ br i1 %cmp, label %if.true, label %end
+
+if.true:
+ br label %end
+
+end:
+ %p = phi float [ 1.0, %entry ], [ %f, %if.true]
+ %c = fcmp ueq float %p, 1.0
+ ret i1 %c
+}
+
+
+define i1 @float.4_unreachable(float %f, i1 %cmp) {
+; CHECK-LABEL: define i1 @float.4_unreachable(float %f, i1 %cmp)
+
+; CHECK-LABEL: end:
+; CHECK-NEXT: ret i1 false
+;
+entry:
+ br i1 %cmp, label %if.true, label %end
+
+if.true:
+ br label %end
+
+dead:
+ br label %end
+
+end:
+ %p = phi float [ 1.0, %entry ], [ 1.0, %if.true], [ %f, %dead ]
+ %c = fcmp une float %p, 1.0
+ ret i1 %c
+}
diff --git a/llvm/test/Transforms/SCCP/range-and.ll b/llvm/test/Transforms/SCCP/range-and.ll
index 84296b94f463..3b349692db70 100644
--- a/llvm/test/Transforms/SCCP/range-and.ll
+++ b/llvm/test/Transforms/SCCP/range-and.ll
@@ -141,8 +141,7 @@ define i1 @constant_range_and_255_100(i1 %cond, i64 %a) {
; CHECK: bb3:
; CHECK-NEXT: [[P:%.*]] = phi i64 [ [[R_1]], [[BB1]] ], [ [[R_2]], [[BB2]] ]
; CHECK-NEXT: [[P_AND:%.*]] = and i64 [[P]], 512
-; CHECK-NEXT: [[C:%.*]] = icmp ult i64 [[P_AND]], 256
-; CHECK-NEXT: ret i1 [[C]]
+; CHECK-NEXT: ret i1 true
;
entry:
br i1 %cond, label %bb1, label %bb2
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