InstCombine: Restrict computeKnownBits() on all Values to OptLevel > 2
As part of r251146 InstCombine was extended to call computeKnownBits on
every value in the function to determine whether it happens to be
constant. This increases typical compiletime by 1-3% (5% in irgen+opt
time) in my measurements. On the other hand this case did not trigger
once in the whole llvm-testsuite.
This patch introduces the notion of ExpensiveCombines which are only
enabled for OptLevel > 2. I removed the check in InstructionSimplify as
that is called from various places where the OptLevel is not known but
given the rarity of the situation I think a check in InstCombine is
enough.
Differential Revision: http://reviews.llvm.org/D16835
llvm-svn: 263047
diff --git a/llvm/test/Analysis/ValueTracking/known-bits-from-range-md.ll b/llvm/test/Analysis/ValueTracking/known-bits-from-range-md.ll
index e1de089b..3bd8c28 100644
--- a/llvm/test/Analysis/ValueTracking/known-bits-from-range-md.ll
+++ b/llvm/test/Analysis/ValueTracking/known-bits-from-range-md.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -instsimplify < %s | FileCheck %s
+; RUN: opt -S -instsimplify -instcombine < %s | FileCheck %s
define i1 @test0(i8* %ptr) {
; CHECK-LABEL: @test0(
@@ -23,10 +23,10 @@
define i1 @test2(i8* %ptr) {
; CHECK-LABEL: @test2(
entry:
-; CHECK: load
-; CHECK: and
-; CHECK: icmp eq
-; CHECK: ret
+; CHECK: %val = load i8
+; CHECK: %and = and i8 %val
+; CHECK: %is.eq = icmp ne i8 %and, 0
+; CHECK: ret i1 %is.eq
%val = load i8, i8* %ptr, !range !{i8 64, i8 129}
%and = and i8 %val, 64
%is.eq = icmp eq i8 %and, 64
diff --git a/llvm/test/Transforms/InstCombine/all-bits-shift.ll b/llvm/test/Transforms/InstCombine/all-bits-shift.ll
index b9eb19c..a035f53 100644
--- a/llvm/test/Transforms/InstCombine/all-bits-shift.ll
+++ b/llvm/test/Transforms/InstCombine/all-bits-shift.ll
@@ -1,5 +1,4 @@
-; RUN: opt -S -instcombine < %s | FileCheck %s
-; RUN: opt -S -instsimplify < %s | FileCheck %s
+; RUN: opt -S -instcombine -expensive-combines < %s | FileCheck %s
target datalayout = "E-m:e-i64:64-n32:64"
target triple = "powerpc64-unknown-linux-gnu"