teach SCEV analysis of PHI nodes that PHI recurences formed

with GEP instructions are always NUW, because PHIs cannot wrap
the end of the address space.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123105 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index fa828acc5be12089e047c4a8923964fa299f6c56..b675e286bad87fe3f023c80dc16d332612ec114d 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2719,6 +2719,11 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
                   HasNUW = true;
                 if (OBO->hasNoSignedWrap())
                   HasNSW = true;
+              } else if (isa<GEPOperator>(BEValueV)) {
+                // If the increment is a GEP, then we know it won't perform an
+                // unsigned overflow, because the address space cannot be
+                // wrapped around.
+                HasNUW = true;
               }
 
               const SCEV *StartVal = getSCEV(StartValueV);

diff --git a/test/Analysis/ScalarEvolution/nsw.ll b/test/Analysis/ScalarEvolution/nsw.ll
index c4b48ee1c7e617ab518672de682078bd4415365c..530ed39ac1c099286aa0339859b8ef0f89f86a90 100644 (file)
--- a/test/Analysis/ScalarEvolution/nsw.ll
+++ b/test/Analysis/ScalarEvolution/nsw.ll
@@ -1,10 +1,11 @@
-; RUN: opt < %s -analyze -scalar-evolution | grep { -->  {.*,+,.*}.*<%bb>} | count 8
+; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
 
 ; The addrecs in this loop are analyzable only by using nsw information.
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64"
 
-define void @foo(double* %p) nounwind {
+; CHECK: Classifying expressions for: @test1
+define void @test1(double* %p) nounwind {
 entry:
        %tmp = load double* %p, align 8         ; <double> [#uses=1]
        %tmp1 = fcmp ogt double %tmp, 2.000000e+00              ; <i1> [#uses=1]
@@ -15,19 +16,29 @@ bb.nph:             ; preds = %entry
 
 bb:            ; preds = %bb1, %bb.nph
        %i.01 = phi i32 [ %tmp8, %bb1 ], [ 0, %bb.nph ]         ; <i32> [#uses=3]
+; CHECK: %i.01
+; CHECK-NEXT: -->  {0,+,1}<nuw><nsw><%bb>
        %tmp2 = sext i32 %i.01 to i64           ; <i64> [#uses=1]
        %tmp3 = getelementptr double* %p, i64 %tmp2             ; <double*> [#uses=1]
        %tmp4 = load double* %tmp3, align 8             ; <double> [#uses=1]
        %tmp5 = fmul double %tmp4, 9.200000e+00         ; <double> [#uses=1]
        %tmp6 = sext i32 %i.01 to i64           ; <i64> [#uses=1]
        %tmp7 = getelementptr double* %p, i64 %tmp6             ; <double*> [#uses=1]
+; CHECK: %tmp7
+; CHECK-NEXT:   -->  {%p,+,8}<%bb>
        store double %tmp5, double* %tmp7, align 8
        %tmp8 = add nsw i32 %i.01, 1            ; <i32> [#uses=2]
+; CHECK: %tmp8
+; CHECK-NEXT: -->  {1,+,1}<nuw><nsw><%bb>
        br label %bb1
 
 bb1:           ; preds = %bb
        %phitmp = sext i32 %tmp8 to i64         ; <i64> [#uses=1]
+; CHECK: %phitmp
+; CHECK-NEXT: -->  {1,+,1}<%bb>
        %tmp9 = getelementptr double* %p, i64 %phitmp           ; <double*> [#uses=1]
+; CHECK: %tmp9
+; CHECK-NEXT:  -->  {(8 + %p),+,8}<%bb>
        %tmp10 = load double* %tmp9, align 8            ; <double> [#uses=1]
        %tmp11 = fcmp ogt double %tmp10, 2.000000e+00           ; <i1> [#uses=1]
        br i1 %tmp11, label %bb, label %bb1.return_crit_edge
@@ -38,3 +49,30 @@ bb1.return_crit_edge:                ; preds = %bb1
 return:                ; preds = %bb1.return_crit_edge, %entry
        ret void
 }
+
+; CHECK: Classifying expressions for: @test2
+define void @test2(i32* %begin, i32* %end) ssp {
+entry:
+  %cmp1.i.i = icmp eq i32* %begin, %end
+  br i1 %cmp1.i.i, label %_ZSt4fillIPiiEvT_S1_RKT0_.exit, label %for.body.lr.ph.i.i
+
+for.body.lr.ph.i.i:                               ; preds = %entry
+  br label %for.body.i.i
+
+for.body.i.i:                                     ; preds = %for.body.i.i, %for.body.lr.ph.i.i
+  %__first.addr.02.i.i = phi i32* [ %begin, %for.body.lr.ph.i.i ], [ %ptrincdec.i.i, %for.body.i.i ]
+; CHECK: %__first.addr.02.i.i
+; CHECK-NEXT: -->  {%begin,+,4}<nuw><%for.body.i.i>    
+  store i32 0, i32* %__first.addr.02.i.i, align 4
+  %ptrincdec.i.i = getelementptr inbounds i32* %__first.addr.02.i.i, i64 1
+; CHECK: %ptrincdec.i.i
+; CHECK-NEXT: -->  {(4 + %begin),+,4}<nuw><%for.body.i.i>
+  %cmp.i.i = icmp eq i32* %ptrincdec.i.i, %end
+  br i1 %cmp.i.i, label %for.cond.for.end_crit_edge.i.i, label %for.body.i.i
+
+for.cond.for.end_crit_edge.i.i:                   ; preds = %for.body.i.i
+  br label %_ZSt4fillIPiiEvT_S1_RKT0_.exit
+
+_ZSt4fillIPiiEvT_S1_RKT0_.exit:                   ; preds = %entry, %for.cond.for.end_crit_edge.i.i
+  ret void
+}