From: Nikita Popov <nikita.ppv@gmail.com>
Date: Sat, 7 Sep 2019 12:03:59 +0000 (+0000)
Subject: [LVI] Look through extractvalue of insertvalue
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=81460d13a7bb587c53fe5506217006c8160be9f4;p=llvm

[LVI] Look through extractvalue of insertvalue

This addresses the issue mentioned on D19867. When we simplify
with.overflow instructions in CVP, we leave behind extractvalue
of insertvalue sequences that LVI no longer understands. This
means that we can not simplify any instructions based on the
with.overflow anymore (until some over pass like InstCombine
cleans them up).

This patch extends LVI extractvalue handling by calling
SimplifyExtractValueInst (which doesn't do anything more than
constant folding + looking through insertvalue) and using the block
value of the simplification.

A possible alternative would be to do something similar to
SimplifyIndVars, where we instead directly try to replace
extractvalue users of the with.overflow. This would need some
additional structural changes to CVP, as it's currently not legal
to remove anything but the current instruction -- we'd have to
introduce a worklist with instructions scheduled for deletion or similar.

Differential Revision: https://reviews.llvm.org/D67035

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@371306 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/LazyValueInfo.cpp b/lib/Analysis/LazyValueInfo.cpp
index 541fc876a21..96722f32e35 100644
--- a/lib/Analysis/LazyValueInfo.cpp
+++ b/lib/Analysis/LazyValueInfo.cpp
@@ -1141,6 +1141,21 @@ bool LazyValueInfoImpl::solveBlockValueExtractValue(
     if (EVI->getNumIndices() == 1 && *EVI->idx_begin() == 0)
       return solveBlockValueOverflowIntrinsic(BBLV, WO, BB);
 
+  // Handle extractvalue of insertvalue to allow further simplification
+  // based on replaced with.overflow intrinsics.
+  if (Value *V = SimplifyExtractValueInst(
+          EVI->getAggregateOperand(), EVI->getIndices(),
+          EVI->getModule()->getDataLayout())) {
+    if (!hasBlockValue(V, BB)) {
+      if (pushBlockValue({ BB, V }))
+        return false;
+      BBLV = ValueLatticeElement::getOverdefined();
+      return true;
+    }
+    BBLV = getBlockValue(V, BB);
+    return true;
+  }
+
   LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()
                     << "' - overdefined (unknown extractvalue).\n");
   BBLV = ValueLatticeElement::getOverdefined();
diff --git a/test/Transforms/CorrelatedValuePropagation/overflows.ll b/test/Transforms/CorrelatedValuePropagation/overflows.ll
index 7f021a47f64..39964682bf2 100644
--- a/test/Transforms/CorrelatedValuePropagation/overflows.ll
+++ b/test/Transforms/CorrelatedValuePropagation/overflows.ll
@@ -850,11 +850,9 @@ define i1 @sadd_and_cmp(i32 %x, i32 %y) #0 {
 ; CHECK-NEXT:    [[ADD:%.*]] = extractvalue { i32, i1 } [[TMP0]], 0
 ; CHECK-NEXT:    br label [[CONT3:%.*]]
 ; CHECK:       cont3:
-; CHECK-NEXT:    [[CMP3:%.*]] = icmp slt i32 [[ADD]], 19
 ; CHECK-NEXT:    br label [[OUT]]
 ; CHECK:       out:
-; CHECK-NEXT:    [[RET:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ true, [[CONT1]] ], [ [[CMP3]], [[CONT3]] ]
-; CHECK-NEXT:    ret i1 [[RET]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %x.offset = add i32 %x, 9
@@ -897,11 +895,9 @@ define i1 @uadd_and_cmp(i32 %x, i32 %y) #0 {
 ; CHECK-NEXT:    [[ADD:%.*]] = extractvalue { i32, i1 } [[TMP0]], 0
 ; CHECK-NEXT:    br label [[CONT3:%.*]]
 ; CHECK:       cont3:
-; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult i32 [[ADD]], 19
 ; CHECK-NEXT:    br label [[OUT]]
 ; CHECK:       out:
-; CHECK-NEXT:    [[RET:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ true, [[CONT1]] ], [ [[CMP3]], [[CONT3]] ]
-; CHECK-NEXT:    ret i1 [[RET]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %cmp1 = icmp ult i32 %x, 10
@@ -940,11 +936,9 @@ define i1 @ssub_and_cmp(i32 %x, i32 %y) #0 {
 ; CHECK-NEXT:    [[SUB:%.*]] = extractvalue { i32, i1 } [[TMP0]], 0
 ; CHECK-NEXT:    br label [[CONT3:%.*]]
 ; CHECK:       cont3:
-; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult i32 [[SUB]], 19
 ; CHECK-NEXT:    br label [[OUT]]
 ; CHECK:       out:
-; CHECK-NEXT:    [[RET:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ true, [[CONT1]] ], [ [[CMP3]], [[CONT3]] ]
-; CHECK-NEXT:    ret i1 [[RET]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %cmp1 = icmp ult i32 %x, 10
@@ -985,11 +979,9 @@ define i1 @usub_and_cmp(i32 %x, i32 %y) #0 {
 ; CHECK-NEXT:    [[SUB:%.*]] = extractvalue { i32, i1 } [[TMP0]], 0
 ; CHECK-NEXT:    br label [[CONT3:%.*]]
 ; CHECK:       cont3:
-; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult i32 [[SUB]], 19
 ; CHECK-NEXT:    br label [[OUT]]
 ; CHECK:       out:
-; CHECK-NEXT:    [[RET:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ true, [[CONT1]] ], [ [[CMP3]], [[CONT3]] ]
-; CHECK-NEXT:    ret i1 [[RET]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %cmp1 = icmp ult i32 %x, 10
@@ -1031,13 +1023,10 @@ define i1 @smul_and_cmp(i32 %x, i32 %y) #0 {
 ; CHECK-NEXT:    [[MUL:%.*]] = extractvalue { i32, i1 } [[TMP0]], 0
 ; CHECK-NEXT:    br label [[CONT3:%.*]]
 ; CHECK:       cont3:
-; CHECK-NEXT:    [[CMP3:%.*]] = icmp sle i32 [[MUL]], 81
-; CHECK-NEXT:    [[CMP4:%.*]] = icmp sge i32 [[MUL]], -81
-; CHECK-NEXT:    [[CMP5:%.*]] = and i1 [[CMP3]], [[CMP4]]
+; CHECK-NEXT:    [[CMP5:%.*]] = and i1 true, true
 ; CHECK-NEXT:    br label [[OUT]]
 ; CHECK:       out:
-; CHECK-NEXT:    [[RET:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ true, [[CONT1]] ], [ [[CMP5]], [[CONT3]] ]
-; CHECK-NEXT:    ret i1 [[RET]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %x.offset = add i32 %x, 9
@@ -1080,11 +1069,9 @@ define i1 @umul_and_cmp(i32 %x, i32 %y) #0 {
 ; CHECK-NEXT:    [[MUL:%.*]] = extractvalue { i32, i1 } [[TMP0]], 0
 ; CHECK-NEXT:    br label [[CONT3:%.*]]
 ; CHECK:       cont3:
-; CHECK-NEXT:    [[CMP3:%.*]] = icmp ule i32 [[MUL]], 9801
 ; CHECK-NEXT:    br label [[OUT]]
 ; CHECK:       out:
-; CHECK-NEXT:    [[RET:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ true, [[CONT1]] ], [ [[CMP3]], [[CONT3]] ]
-; CHECK-NEXT:    ret i1 [[RET]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %cmp1 = icmp ult i32 %x, 100