From 926b3b9ee3d1a6d08160d17ca36f8198020411c5 Mon Sep 17 00:00:00 2001
From: Matt Pharr <matt.pharr@intel.com>
Date: Mon, 9 Jul 2012 15:13:30 -0700
Subject: [PATCH] Fix bugs with mask-handling for switch/do/for/while
 statements.

All of these pass the current mask to FunctionEmitContext::SetBlockEntryMask()
so that when a break/continue/return is encountered, it can test to see if all
lanes have followed that path and then return; this in turn ensures that we never
run statements with an all-off execution mask.

These functions were passing the function internal mask, not the full mask, and
thus could end up executing code with the mask all off if some lanes were
disabled by an outer function.  (The new tests test this case.)
---
 stmt.cpp                     |  6 +++---
 tests/entry-mask-do.ispc     | 30 ++++++++++++++++++++++++++++++
 tests/entry-mask-for.ispc    | 30 ++++++++++++++++++++++++++++++
 tests/entry-mask-switch.ispc | 30 ++++++++++++++++++++++++++++++
 4 files changed, 93 insertions(+), 3 deletions(-)
 create mode 100644 tests/entry-mask-do.ispc
 create mode 100644 tests/entry-mask-for.ispc
 create mode 100644 tests/entry-mask-switch.ispc

diff --git a/stmt.cpp b/stmt.cpp
index 7a547149..04807faf 100644
--- a/stmt.cpp
+++ b/stmt.cpp
@@ -830,7 +830,7 @@ void DoStmt::EmitCode(FunctionEmitContext *ctx) const {
 
     // And now emit code for the loop body
     ctx->SetCurrentBasicBlock(bloop);
-    ctx->SetBlockEntryMask(ctx->GetInternalMask());
+    ctx->SetBlockEntryMask(ctx->GetFullMask());
     ctx->SetDebugPos(pos);
     // FIXME: in the StmtList::EmitCode() method takes starts/stops a new
     // scope around the statements in the list.  So if the body is just a
@@ -1047,7 +1047,7 @@ ForStmt::EmitCode(FunctionEmitContext *ctx) const {
 
     // On to emitting the code for the loop body.
     ctx->SetCurrentBasicBlock(bloop);
-    ctx->SetBlockEntryMask(ctx->GetInternalMask());
+    ctx->SetBlockEntryMask(ctx->GetFullMask());
     ctx->AddInstrumentationPoint("for loop body");
     if (!dynamic_cast<StmtList *>(stmts))
         ctx->StartScope();
@@ -2555,7 +2555,7 @@ SwitchStmt::EmitCode(FunctionEmitContext *ctx) const {
     bool isUniformCF = (type->IsUniformType() &&
                         lHasVaryingBreakOrContinue(stmts) == false);
     ctx->StartSwitch(isUniformCF, bbDone);
-    ctx->SetBlockEntryMask(ctx->GetInternalMask());
+    ctx->SetBlockEntryMask(ctx->GetFullMask());
     ctx->SwitchInst(exprValue, svi.defaultBlock ? svi.defaultBlock : bbDone,
                     svi.caseBlocks, svi.nextBlock);
 
diff --git a/tests/entry-mask-do.ispc b/tests/entry-mask-do.ispc
new file mode 100644
index 00000000..dd2254b3
--- /dev/null
+++ b/tests/entry-mask-do.ispc
@@ -0,0 +1,30 @@
+
+export uniform int width() { return programCount; }
+
+int * uniform ptr = NULL;
+
+int func(int v) {
+    int ret;
+    //    print("%\n", v);
+    do {
+        if (v == 0) {
+            ret = 1;
+            break;
+        }
+        *ptr = 1;
+    } while(true);
+    return ret;
+}
+
+export void f_f(uniform float RET[], uniform float aFOO[]) {
+    int count = 10;
+    if (programIndex & 1)
+        count = 0x7ffffff;
+    RET[programIndex] = 0;
+    if (!(programIndex & 1))
+        RET[programIndex] = func(programIndex & 1);
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = !(programIndex & 1);
+}
diff --git a/tests/entry-mask-for.ispc b/tests/entry-mask-for.ispc
new file mode 100644
index 00000000..a04642c7
--- /dev/null
+++ b/tests/entry-mask-for.ispc
@@ -0,0 +1,30 @@
+
+export uniform int width() { return programCount; }
+
+int * uniform ptr = NULL;
+
+int func(int v) {
+    int ret;
+    //    print("%\n", v);
+    for (;;) {
+        if (v == 0) {
+            ret = 1;
+            break;
+        }
+        *ptr = 1;
+    }
+    return ret;
+}
+
+export void f_f(uniform float RET[], uniform float aFOO[]) {
+    int count = 10;
+    if (programIndex & 1)
+        count = 0x7ffffff;
+    RET[programIndex] = 0;
+    if (!(programIndex & 1))
+        RET[programIndex] = func(programIndex & 1);
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = !(programIndex & 1);
+}
diff --git a/tests/entry-mask-switch.ispc b/tests/entry-mask-switch.ispc
new file mode 100644
index 00000000..541f1487
--- /dev/null
+++ b/tests/entry-mask-switch.ispc
@@ -0,0 +1,30 @@
+
+export uniform int width() { return programCount; }
+
+int * uniform ptr = NULL;
+
+int func(int v) {
+    int ret;
+    //    print("%\n", v);
+    switch (v) {
+    case 0:
+        ret = 1;
+        break;
+    case 1:
+        *ptr = 1;
+    }
+    return ret;
+}
+
+export void f_f(uniform float RET[], uniform float aFOO[]) {
+    int count = 10;
+    if (programIndex & 1)
+        count = 0x7ffffff;
+    RET[programIndex] = 0;
+    if (!(programIndex & 1))
+        RET[programIndex] = func(programIndex & 1);
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = !(programIndex & 1);
+}