[llvm] r334736 - [SCEV] Simplify trunc-of-add/mul to add/mul-of-trunc under more circumstances.
Justin Lebar via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 14 10:13:35 PDT 2018
Author: jlebar
Date: Thu Jun 14 10:13:35 2018
New Revision: 334736
URL: http://llvm.org/viewvc/llvm-project?rev=334736&view=rev
Log:
[SCEV] Simplify trunc-of-add/mul to add/mul-of-trunc under more circumstances.
Summary:
Previously we would do this simplification only if it did not introduce
any new truncs (excepting new truncs which replace other cast ops).
This change weakens this condition: If the number of truncs stays the
same, but we're able to transform trunc(X + Y) to X + trunc(Y), that's
still simpler, and it may open up additional transformations.
While we're here, also clean up some duplicated code.
Reviewers: sanjoy
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D48160
Added:
llvm/trunk/test/Analysis/ScalarEvolution/trunc-simplify.ll
Modified:
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
llvm/trunk/test/Analysis/ScalarEvolution/different-loops-recs.ll
llvm/trunk/test/Analysis/ScalarEvolution/max-trip-count-address-space.ll
llvm/trunk/test/Analysis/ScalarEvolution/sext-inreg.ll
llvm/trunk/test/Analysis/ScalarEvolution/strip-injective-zext.ll
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=334736&r1=334735&r2=334736&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Thu Jun 14 10:13:35 2018
@@ -1256,42 +1256,32 @@ const SCEV *ScalarEvolution::getTruncate
if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
return getTruncateOrZeroExtend(SZ->getOperand(), Ty);
- // trunc(x1+x2+...+xN) --> trunc(x1)+trunc(x2)+...+trunc(xN) if we can
- // eliminate all the truncates, or we replace other casts with truncates.
- if (const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Op)) {
+ // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and
+ // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN),
+ // if after transforming we have at most one truncate, not counting truncates
+ // that replace other casts.
+ if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) {
+ auto *CommOp = cast<SCEVCommutativeExpr>(Op);
SmallVector<const SCEV *, 4> Operands;
- bool hasTrunc = false;
- for (unsigned i = 0, e = SA->getNumOperands(); i != e && !hasTrunc; ++i) {
- const SCEV *S = getTruncateExpr(SA->getOperand(i), Ty);
- if (!isa<SCEVCastExpr>(SA->getOperand(i)))
- hasTrunc = isa<SCEVTruncateExpr>(S);
+ unsigned numTruncs = 0;
+ for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2;
+ ++i) {
+ const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty);
+ if (!isa<SCEVCastExpr>(CommOp->getOperand(i)) && isa<SCEVTruncateExpr>(S))
+ numTruncs++;
Operands.push_back(S);
}
- if (!hasTrunc)
- return getAddExpr(Operands);
- // In spite we checked in the beginning that ID is not in the cache,
- // it is possible that during recursion and different modification
- // ID came to cache, so if we found it, just return it.
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
- return S;
- }
-
- // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can
- // eliminate all the truncates, or we replace other casts with truncates.
- if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) {
- SmallVector<const SCEV *, 4> Operands;
- bool hasTrunc = false;
- for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) {
- const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty);
- if (!isa<SCEVCastExpr>(SM->getOperand(i)))
- hasTrunc = isa<SCEVTruncateExpr>(S);
- Operands.push_back(S);
+ if (numTruncs < 2) {
+ if (isa<SCEVAddExpr>(Op))
+ return getAddExpr(Operands);
+ else if (isa<SCEVMulExpr>(Op))
+ return getMulExpr(Operands);
+ else
+ llvm_unreachable("Unexpected SCEV type for Op.");
}
- if (!hasTrunc)
- return getMulExpr(Operands);
- // In spite we checked in the beginning that ID is not in the cache,
- // it is possible that during recursion and different modification
- // ID came to cache, so if we found it, just return it.
+ // Although we checked in the beginning that ID is not in the cache, it is
+ // possible that during recursion and different modification ID was inserted
+ // into the cache. So if we find it, just return it.
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
return S;
}
Modified: llvm/trunk/test/Analysis/ScalarEvolution/different-loops-recs.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/different-loops-recs.ll?rev=334736&r1=334735&r2=334736&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/different-loops-recs.ll (original)
+++ llvm/trunk/test/Analysis/ScalarEvolution/different-loops-recs.ll Thu Jun 14 10:13:35 2018
@@ -277,9 +277,10 @@ define void @test_04() {
; CHECK: %tmp11 = add i64 %tmp10, undef
; CHECK-NEXT: --> ((sext i8 %tmp8 to i64) + {(-2 + undef),+,-1}<nw><%loop2>)
; CHECK: %tmp13 = trunc i64 %tmp11 to i32
-; CHECK-NEXT: --> ((sext i8 %tmp8 to i32) + {(trunc i64 (-2 + undef) to i32),+,-1}<%loop2>)
+; CHECK-NEXT: --> ((sext i8 %tmp8 to i32) + {(-2 + (trunc i64 undef to i32)),+,-1}<%loop2>)
; CHECK: %tmp14 = sub i32 %tmp13, %tmp2
-; CHECK-NEXT: --> ((sext i8 %tmp8 to i32) + {{{{}}(-2 + (trunc i64 (-2 + undef) to i32)),+,-1}<%loop1>,+,-1}<%loop2>)
+; `{{[{][{]}}` is the ugliness needed to match `{{`
+; CHECK-NEXT: --> ((sext i8 %tmp8 to i32) + {{[{][{]}}(-4 + (trunc i64 undef to i32)),+,-1}<%loop1>,+,-1}<%loop2>)
; CHECK: %tmp15 = add nuw nsw i64 %tmp7, 1
; CHECK-NEXT: --> {3,+,1}<nuw><nsw><%loop2>
@@ -462,9 +463,9 @@ define void @test_08() {
; CHECK: %tmp11 = add i64 %iv.2.2, %iv.2.1
; CHECK-NEXT: --> ({0,+,-1}<nsw><%loop_2> + %iv.2.1)
; CHECK: %tmp12 = trunc i64 %tmp11 to i32
-; CHECK-NEXT: --> (trunc i64 ({0,+,-1}<nsw><%loop_2> + %iv.2.1) to i32)
+; CHECK-NEXT: --> ((trunc i64 %iv.2.1 to i32) + {0,+,-1}<%loop_2>)
; CHECK: %tmp14 = mul i32 %tmp12, %tmp7
-; CHECK-NEXT: --> ((trunc i64 ({0,+,-1}<nsw><%loop_2> + %iv.2.1) to i32) * {-1,+,-1}<%loop_1>)
+; CHECK-NEXT: --> (((trunc i64 %iv.2.1 to i32) + {0,+,-1}<%loop_2>) * {-1,+,-1}<%loop_1>)
; CHECK: %tmp16 = mul i64 %iv.2.1, %iv.1.1
; CHECK-NEXT: --> ({2,+,1}<nuw><nsw><%loop_1> * %iv.2.1)
Modified: llvm/trunk/test/Analysis/ScalarEvolution/max-trip-count-address-space.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/max-trip-count-address-space.ll?rev=334736&r1=334735&r2=334736&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/max-trip-count-address-space.ll (original)
+++ llvm/trunk/test/Analysis/ScalarEvolution/max-trip-count-address-space.ll Thu Jun 14 10:13:35 2018
@@ -4,7 +4,7 @@
target datalayout = "e-p:32:32:32-p1:16:16:16-p2:8:8:8-p4:64:64:64-n16:32:64"
-; CHECK: {%d,+,4}<%bb>{{ U: [^ ]+ S: [^ ]+}}{{ *}}Exits: ((4 * (trunc i32 (-1 + %n) to i16)) + %d)
+; CHECK: {%d,+,4}<%bb>{{ U: [^ ]+ S: [^ ]+}}{{ *}} Exits: (-4 + (4 * (trunc i32 %n to i16)) + %d)
define void @foo(i32 addrspace(1)* nocapture %d, i32 %n) nounwind {
Modified: llvm/trunk/test/Analysis/ScalarEvolution/sext-inreg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/sext-inreg.ll?rev=334736&r1=334735&r2=334736&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/sext-inreg.ll (original)
+++ llvm/trunk/test/Analysis/ScalarEvolution/sext-inreg.ll Thu Jun 14 10:13:35 2018
@@ -15,10 +15,10 @@ bb:
%t2 = ashr i64 %t1, 7
; CHECK: %t2 = ashr i64 %t1, 7
; CHECK-NEXT: sext i57 {0,+,199}<%bb> to i64
-; CHECK-SAME: Exits: (sext i57 (199 * (trunc i64 (-1 + (2780916192016515319 * %n)) to i57)) to i64)
+; CHECK-SAME: Exits: (sext i57 (-199 + (trunc i64 %n to i57)) to i64)
; CHECK: %s2 = ashr i64 %s1, 5
; CHECK-NEXT: sext i59 {0,+,199}<%bb> to i64
-; CHECK-SAME: Exits: (sext i59 (199 * (trunc i64 (-1 + (2780916192016515319 * %n)) to i59)) to i64)
+; CHECK-SAME: Exits: (sext i59 (-199 + (trunc i64 %n to i59)) to i64)
%s1 = shl i64 %i.01, 5
%s2 = ashr i64 %s1, 5
%t3 = getelementptr i64, i64* %x, i64 %i.01
Modified: llvm/trunk/test/Analysis/ScalarEvolution/strip-injective-zext.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/strip-injective-zext.ll?rev=334736&r1=334735&r2=334736&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/strip-injective-zext.ll (original)
+++ llvm/trunk/test/Analysis/ScalarEvolution/strip-injective-zext.ll Thu Jun 14 10:13:35 2018
@@ -9,7 +9,7 @@
; Check that the backedge taken count was actually computed:
; CHECK: Determining loop execution counts for: @f0
-; CHECK-NEXT: Loop %b2: backedge-taken count is (-1 * (trunc i32 (1 + %a1) to i2))
+; CHECK-NEXT: Loop %b2: backedge-taken count is (-1 + (-1 * (trunc i32 %a1 to i2)))
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64"
Added: llvm/trunk/test/Analysis/ScalarEvolution/trunc-simplify.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/trunc-simplify.ll?rev=334736&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/trunc-simplify.ll (added)
+++ llvm/trunk/test/Analysis/ScalarEvolution/trunc-simplify.ll Thu Jun 14 10:13:35 2018
@@ -0,0 +1,25 @@
+; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
+
+; Check that we convert
+; trunc(C * a) -> trunc(C) * trunc(a)
+; if C is a constant.
+; CHECK-LABEL: @trunc_of_mul
+define i8 @trunc_of_mul(i32 %a) {
+ %b = mul i32 %a, 100
+ ; CHECK: %c
+ ; CHECK-NEXT: --> (100 * (trunc i32 %a to i8))
+ %c = trunc i32 %b to i8
+ ret i8 %c
+}
+
+; Check that we convert
+; trunc(C + a) -> trunc(C) + trunc(a)
+; if C is a constant.
+; CHECK-LABEL: @trunc_of_add
+define i8 @trunc_of_add(i32 %a) {
+ %b = add i32 %a, 100
+ ; CHECK: %c
+ ; CHECK-NEXT: --> (100 + (trunc i32 %a to i8))
+ %c = trunc i32 %b to i8
+ ret i8 %c
+}
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