[llvm] r334567 - [SimplifyIndVars] Ignore dead users
Mikael Holmén via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 6 02:20:24 PDT 2018
Hi Max,
We foudn a case that started crashing with this commit. I wrote
https://bugs.llvm.org/show_bug.cgi?id=38855
about it.
/Mikael
On 06/13/2018 04:25 AM, Max Kazantsev via llvm-commits wrote:
> Author: mkazantsev
> Date: Tue Jun 12 19:25:32 2018
> New Revision: 334567
>
> URL: http://llvm.org/viewvc/llvm-project?rev=334567&view=rev
> Log:
> [SimplifyIndVars] Ignore dead users
>
> IndVarSimplify sometimes makes transforms basing on users that are trivially dead. In particular,
> if DCE wasn't run before it, there may be a dead `sext/zext` in loop that will trigger widening
> transforms, however it makes no sense to do it.
>
> This patch teaches IndVarsSimplify ignore the mist trivial cases of that.
>
> Differential Revision: https://reviews.llvm.org/D47974
> Reviewed By: sanjoy
>
> Modified:
> llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp
> llvm/trunk/test/Analysis/ScalarEvolution/2012-05-29-MulAddRec.ll
> llvm/trunk/test/Analysis/ScalarEvolution/guards.ll
> llvm/trunk/test/Transforms/IndVarSimplify/2011-09-10-widen-nsw.ll
> llvm/trunk/test/Transforms/IndVarSimplify/iv-widen.ll
> llvm/trunk/test/Transforms/IndVarSimplify/lftr-reuse.ll
> llvm/trunk/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll
> llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
> llvm/trunk/test/Transforms/IndVarSimplify/pr25578.ll
>
> Modified: llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp Tue Jun 12 19:25:32 2018
> @@ -26,6 +26,7 @@
> #include "llvm/IR/PatternMatch.h"
> #include "llvm/Support/Debug.h"
> #include "llvm/Support/raw_ostream.h"
> +#include "llvm/Transforms/Utils/Local.h"
>
> using namespace llvm;
>
> @@ -772,6 +773,15 @@ void SimplifyIndvar::simplifyUsers(PHINo
> SimpleIVUsers.pop_back_val();
> Instruction *UseInst = UseOper.first;
>
> + // If a user of the IndVar is trivially dead, we prefer just to mark it dead
> + // rather than try to do some complex analysis or transformation (such as
> + // widening) basing on it.
> + // TODO: Propagate TLI and pass it here to handle more cases.
> + if (isInstructionTriviallyDead(UseInst, /* TLI */ nullptr)) {
> + DeadInsts.emplace_back(UseInst);
> + continue;
> + }
> +
> // Bypass back edges to avoid extra work.
> if (UseInst == CurrIV) continue;
>
>
> Modified: llvm/trunk/test/Analysis/ScalarEvolution/2012-05-29-MulAddRec.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/2012-05-29-MulAddRec.ll?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/test/Analysis/ScalarEvolution/2012-05-29-MulAddRec.ll (original)
> +++ llvm/trunk/test/Analysis/ScalarEvolution/2012-05-29-MulAddRec.ll Tue Jun 12 19:25:32 2018
> @@ -8,6 +8,8 @@
> ;
> ; PR12929: cast<Ty>() argument of incompatible type
>
> +declare void @use(i8 %x)
> +
> ; CHECK: @func
> ; CHECK: for.cond:
> ; CHECK: %inc1 = phi i8 [ 0, %entry ], [ %0, %for.body ]
> @@ -33,6 +35,7 @@ for.cond:
> %indvars.iv = phi i8 [ %indvars.iv.next, %for.cond.loopexit ], [ 10, %entry ]
> %mul3 = phi i8 [ undef, %entry ], [ %mul.lcssa, %for.cond.loopexit ]
> %inc1 = phi i8 [ 0, %entry ], [ %0, %for.cond.loopexit ]
> + call void @use(i8 %inc1)
> br label %for.body
>
> for.body: ; preds = %for.body, %for.cond
> @@ -40,6 +43,7 @@ for.body:
> %mul45 = phi i8 [ %mul3, %for.cond ], [ %mul, %for.body ]
> %inc = add i8 %inc26, 1
> %mul = mul i8 %inc26, %mul45
> + call void @use(i8 %inc)
> %exitcond = icmp ne i8 %inc, %indvars.iv
> br i1 %exitcond, label %for.body, label %for.cond.loopexit
> }
>
> Modified: llvm/trunk/test/Analysis/ScalarEvolution/guards.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/guards.ll?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/test/Analysis/ScalarEvolution/guards.ll (original)
> +++ llvm/trunk/test/Analysis/ScalarEvolution/guards.ll Tue Jun 12 19:25:32 2018
> @@ -10,6 +10,8 @@ target datalayout = "n8:16:32:64"
>
> declare void @llvm.experimental.guard(i1, ...)
>
> +declare void @use(i64 %x)
> +
> define void @test_1(i1* %cond_buf, i32* %len_buf) {
> ; CHECK-LABEL: @test_1(
> entry:
> @@ -60,6 +62,7 @@ loop:
> %iv.inc = add i32 %iv, 1
>
> %iv.sext = sext i32 %iv to i64
> + call void @use(i64 %iv.sext)
>
> %iv.inc.cmp = icmp slt i32 %iv.inc, %len
> call void(i1, ...) @llvm.experimental.guard(i1 %iv.inc.cmp) [ "deopt"() ]
>
> Modified: llvm/trunk/test/Transforms/IndVarSimplify/2011-09-10-widen-nsw.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/2011-09-10-widen-nsw.ll?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/IndVarSimplify/2011-09-10-widen-nsw.ll (original)
> +++ llvm/trunk/test/Transforms/IndVarSimplify/2011-09-10-widen-nsw.ll Tue Jun 12 19:25:32 2018
> @@ -5,6 +5,8 @@
>
> target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
>
> +declare void @use(i64 %x)
> +
> define void @test() nounwind {
> entry:
> br i1 undef, label %for.body11, label %for.end285
> @@ -26,15 +28,19 @@ for.body170:
>
> %add = add nsw i32 %i2.19, 1
> %add.idxprom = sext i32 %add to i64
> + call void @use(i64 %add.idxprom)
>
> %sub = sub nsw i32 %i2.19, 2
> %sub.idxprom = sext i32 %sub to i64
> + call void @use(i64 %sub.idxprom)
>
> %sub.neg = sub nsw i32 4, %i2.19
> %sub.neg.idxprom = sext i32 %sub.neg to i64
> + call void @use(i64 %sub.neg.idxprom)
>
> %mul = mul nsw i32 %i2.19, 8
> %mul.idxprom = sext i32 %mul to i64
> + call void @use(i64 %mul.idxprom)
>
> %add249 = add nsw i32 %i2.19, %shl132
> br label %for.body170
>
> Modified: llvm/trunk/test/Transforms/IndVarSimplify/iv-widen.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/iv-widen.ll?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/IndVarSimplify/iv-widen.ll (original)
> +++ llvm/trunk/test/Transforms/IndVarSimplify/iv-widen.ll Tue Jun 12 19:25:32 2018
> @@ -7,10 +7,12 @@ target datalayout = "n8:16:32:64"
>
> target triple = "x86_64-apple-darwin"
>
> +declare void @use(i64 %x)
> +
> ; CHECK-LABEL: @loop_0
> ; CHECK-LABEL: B18:
> ; Only one phi now.
> -; CHECK: phi
> +; CHECK: phi i64
> ; CHECK-NOT: phi
> ; One trunc for the gep.
> ; CHECK: trunc i64 %indvars.iv to i32
> @@ -21,6 +23,37 @@ define void @loop_0(i32* %a) {
> Prologue:
> br i1 undef, label %B18, label %B6
>
> +B18: ; preds = %B24, %Prologue
> + %.02 = phi i32 [ 0, %Prologue ], [ %tmp33, %B24 ]
> + %tmp23 = zext i32 %.02 to i64
> + call void @use(i64 %tmp23)
> + %tmp33 = add i32 %.02, 1
> + %o = getelementptr i32, i32* %a, i32 %.02
> + %v = load i32, i32* %o
> + %t = icmp eq i32 %v, 0
> + br i1 %t, label %exit24, label %B24
> +
> +B24: ; preds = %B18
> + %t2 = icmp eq i32 %tmp33, 20
> + br i1 %t2, label %B6, label %B18
> +
> +B6: ; preds = %Prologue
> + ret void
> +
> +exit24: ; preds = %B18
> + call void @dummy(i32 %.02)
> + unreachable
> +}
> +
> +; Make sure that dead zext is removed and no widening happens.
> +; CHECK-LABEL: @loop_0.dead
> +; CHECK: phi i32
> +; CHECK-NOT: zext
> +; CHECK-NOT: trunc
> +define void @loop_0.dead(i32* %a) {
> +Prologue:
> + br i1 undef, label %B18, label %B6
> +
> B18: ; preds = %B24, %Prologue
> %.02 = phi i32 [ 0, %Prologue ], [ %tmp33, %B24 ]
> %tmp23 = zext i32 %.02 to i64
>
> Modified: llvm/trunk/test/Transforms/IndVarSimplify/lftr-reuse.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/lftr-reuse.ll?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/IndVarSimplify/lftr-reuse.ll (original)
> +++ llvm/trunk/test/Transforms/IndVarSimplify/lftr-reuse.ll Tue Jun 12 19:25:32 2018
> @@ -6,6 +6,8 @@ target datalayout = "e-p:64:64:64-i1:8:8
>
> ; Perform LFTR using the original pointer-type IV.
>
> +declare void @use(double %x)
> +
> ; for(char* p = base; p < base + n; ++p) {
> ; *p = p-base;
> ; }
> @@ -102,9 +104,11 @@ loop:
> %diagidxw = sext i32 %diagidx to i64
> %matrixp = getelementptr inbounds [0 x double], [0 x double]* %matrix, i32 0, i64 %diagidxw
> %v1 = load double, double* %matrixp
> + call void @use(double %v1)
> %iw = sext i32 %i to i64
> %vectorp = getelementptr inbounds [0 x double], [0 x double]* %vector, i32 0, i64 %iw
> %v2 = load double, double* %vectorp
> + call void @use(double %v2)
> %row.inc = add nsw i32 %rowidx, %ilead
> %i.inc = add nsw i32 %i, 1
> %cmp196 = icmp slt i32 %i.inc, %irow
> @@ -125,7 +129,6 @@ entry:
> ; CHECK-NOT: add
> ; CHECK: loop:
> ; CHECK: phi i64
> -; CHECK: phi i64
> ; CHECK-NOT: phi
> ; CHECK: icmp slt
> ; CHECK: br i1
>
> Modified: llvm/trunk/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll (original)
> +++ llvm/trunk/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll Tue Jun 12 19:25:32 2018
> @@ -293,6 +293,8 @@ for.end:
> ret void
> }
>
> +declare void @use(i1 %x)
> +
> ; check that we handle conditions with loop invariant operands which
> ; *aren't* in the header - this is a very rare and fragile case where
> ; we have a "loop" which is known to run exactly one iteration but
> @@ -320,6 +322,7 @@ latch:
> br i1 true, label %exit, label %loop
>
> exit:
> + call void @use(i1 %cmp)
> ret void
> }
>
>
> Modified: llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll (original)
> +++ llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll Tue Jun 12 19:25:32 2018
> @@ -357,6 +357,9 @@ exit:
> ret void
> }
>
> +declare void @use32(i32 %x)
> +declare void @use64(i64 %x)
> +
> ; Test a widened IV that is used by a phi on different paths within the loop.
> ;
> ; CHECK: for.body:
> @@ -385,10 +388,12 @@ if.else:
>
> if.then97:
> %idxprom100 = sext i32 %iv to i64
> + call void @use64(i64 %idxprom100)
> br label %for.inc
>
> for.inc:
> %kmin.1 = phi i32 [ %iv, %if.then33 ], [ 0, %if.then ], [ %iv, %if.then97 ], [ 0, %if.else ]
> + call void @use32(i32 %kmin.1)
> %inc = add nsw i32 %iv, 1
> br i1 undef, label %for.body, label %for.end
>
>
> Modified: llvm/trunk/test/Transforms/IndVarSimplify/pr25578.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/pr25578.ll?rev=334567&r1=334566&r2=334567&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/IndVarSimplify/pr25578.ll (original)
> +++ llvm/trunk/test/Transforms/IndVarSimplify/pr25578.ll Tue Jun 12 19:25:32 2018
> @@ -1,6 +1,8 @@
> ; RUN: opt < %s -indvars -S | FileCheck %s
> target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
>
> +declare void @use(i64 %x)
> +
> ; CHECK-LABEL: @foo
> define void @foo() {
> entry:
> @@ -15,6 +17,7 @@ L1_header:
> L2_header:
> %i = phi i32 [ 0, %L1_header ], [ %i_next, %L2_latch ]
> %i_prom = sext i32 %i to i64
> + call void @use(i64 %i_prom)
> br label %L3_header
>
> L3_header:
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
More information about the llvm-commits
mailing list