Attachment 115488 Details for Bug 90056 – Possible fix

[patch] Possible fix

0001-R600-SI-Fix-verifier-errors-from-the-SIAnnotateContr.patch (text/plain), 2.93 KB, created by Tom Stellard on 2015-04-30 21:19:03 UTC

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Creator: Tom Stellard

Created: 2015-04-30 21:19:03 UTC

Size: 2.93 KB

patch

obsolete

>From 4d12bcf88b7675d4c6291ee810f8272fedc0d411 Mon Sep 17 00:00:00 2001
>From: Tom Stellard <thomas.stellard@amd.com>
>Date: Thu, 30 Apr 2015 18:51:13 +0000
>Subject: [PATCH] R600/SI: Fix verifier errors from the SIAnnotateControlFlow
> pass
>
>This pass was generating 'Instruction does not dominate all uses!'
>errors for programs which had loops with a condition variable that
>depended on the result of a phi instruction from outside of the loop.
>
>The pass was inserting new phi nodes outside of the loop which used values
>defined inside the loop.
>
>http://bugs.freedesktop.org/show_bug.cgi?id=90056
>---
> lib/Target/R600/SIAnnotateControlFlow.cpp | 10 +++++++-
> test/CodeGen/R600/si-annotate-cf.ll       | 38 +++++++++++++++++++++++++++++++
> 2 files changed, 47 insertions(+), 1 deletion(-)
>
>diff --git a/lib/Target/R600/SIAnnotateControlFlow.cpp b/lib/Target/R600/SIAnnotateControlFlow.cpp
>index d39ab3f..ccfbf1b 100644
>--- a/lib/Target/R600/SIAnnotateControlFlow.cpp
>+++ b/lib/Target/R600/SIAnnotateControlFlow.cpp
>@@ -209,7 +209,15 @@ void SIAnnotateControlFlow::insertElse(BranchInst *Term) {
> /// \brief Recursively handle the condition leading to a loop
> Value *SIAnnotateControlFlow::handleLoopCondition(Value *Cond, PHINode *Broken,
>                                                   llvm::Loop *L) {
>-  if (PHINode *Phi = dyn_cast<PHINode>(Cond)) {
>+
>+  // Only search through PHI nodes which are inside the loop.  If we try this
>+  // with PHI nodes that are outside of the loop, we end up inserting new PHI
>+  // nodes outside of the loop which depend on values defined inside the loop.
>+  // This will break the module with
>+  // 'Instruction does not dominate all users!' errors.
>+  PHINode *Phi = nullptr;
>+  if ((Phi = dyn_cast<PHINode>(Cond)) && L->contains(Phi)) {
>+
>     BasicBlock *Parent = Phi->getParent();
>     PHINode *NewPhi = PHINode::Create(Int64, 0, "", &Parent->front());
>     Value *Ret = NewPhi;
>diff --git a/test/CodeGen/R600/si-annotate-cf.ll b/test/CodeGen/R600/si-annotate-cf.ll
>index 3f30988..bbcb861 100644
>--- a/test/CodeGen/R600/si-annotate-cf.ll
>+++ b/test/CodeGen/R600/si-annotate-cf.ll
>@@ -23,3 +23,41 @@ ENDLOOP:
> ENDIF:
>   br i1 %1, label %ENDLOOP, label %ENDIF
> }
>+
>+
>+; FUNC-LABEL: {{^}}phi_cond_outside_loop:
>+; FIXME: This could be folded into the s_or_b64 instruction
>+; SI: s_mov_b64 [[ZERO:s\[[0-9]+:[0-9]+\]]], 0
>+; SI: [[LOOP_LABEL:[A-Z0-9]+]]
>+; SI: v_cmp_ne_i32_e32 vcc, 0, v{{[0-9]+}}
>+
>+; SI_IF_BREAK instruction:
>+; SI: s_or_b64 [[BREAK:s\[[0-9]+:[0-9]+\]]], vcc, [[ZERO]]
>+
>+; SI_LOOP instruction:
>+; SI: s_andn2_b64 exec, exec, [[BREAK]]
>+; SI: s_cbranch_execnz [[LOOP_LABEL]]
>+; SI: s_endpgm
>+
>+define void @phi_cond_outside_loop(i32 %a, i32 %b) {
>+entry:
>+  %0 = icmp eq i32 %a , 0
>+  br i1 %0, label %if, label %else
>+
>+if:
>+  br label %endif
>+
>+else:
>+  %1 = icmp eq i32 %b, 0
>+  br label %endif
>+
>+endif:
>+  %2 = phi i1 [0, %if], [%1, %else]
>+  br label %loop
>+
>+loop:
>+  br i1 %2, label %exit, label %loop
>+
>+exit:
>+  ret void
>+}
>-- 
>2.0.4
>

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