From c9b67141f0827ccdfefd0197b6f0daba50f35dc2 Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Thu, 27 Aug 2020 11:20:31 +0200
Subject: [PATCH] Add early returns

---
 relapack/src/dgetrf.c      | 12 ++++++------
 relapack/src/dsytrf.c      |  3 ++-
 relapack/src/dsytrf_rook.c |  4 ++--
 relapack/src/dtrsyl.c      |  5 +++++
 relapack/src/zgetrf.c      |  9 +++++++--
 relapack/src/zhetrf_rook.c |  4 ++--
 relapack/src/zsytrf.c      |  3 ++-
 relapack/src/zsytrf_rook.c |  5 +++--
 relapack/src/ztrsyl.c      |  5 +++++
 relapack/src/ztrtri.c      |  4 ++--
 10 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/relapack/src/dgetrf.c b/relapack/src/dgetrf.c
index be960fde9..3ebfb18d2 100644
--- a/relapack/src/dgetrf.c
+++ b/relapack/src/dgetrf.c
@@ -29,15 +29,16 @@ void RELAPACK_dgetrf(
         return;
     }
 
-    const blasint sn = MIN(*m, *n);
+    if (*m == 0 || *n == 0) return;
 
+    const blasint sn = MIN(*m, *n);
     RELAPACK_dgetrf_rec(m, &sn, A, ldA, ipiv, info);
 
     // Right remainder
     if (*m < *n) {
         // Constants
         const double ONE[] = { 1. };
-        const blasint   iONE[] = { 1. };
+        const blasint   iONE[] = { 1 };
 
         // Splitting
         const blasint rn = *n - *m;
@@ -60,13 +61,11 @@ static void RELAPACK_dgetrf_rec(
     double *A, const blasint *ldA, blasint *ipiv,
     blasint *info
 ) {
-
-    if (*n <= MAX(CROSSOVER_DGETRF, 1)) {
+    if ( *n <= MAX(CROSSOVER_DGETRF, 1)) {
         // Unblocked
-        LAPACK(dgetf2)(m, n, A, ldA, ipiv, info);
+        LAPACK(dgetrf2)(m, n, A, ldA, ipiv, info);
         return;
     }
-
     // Constants
     const double ONE[]  = { 1. };
     const double MONE[] = { -1. };
@@ -95,6 +94,7 @@ static void RELAPACK_dgetrf_rec(
 
     // recursion(A_L, ipiv_T)
     RELAPACK_dgetrf_rec(m, &n1, A_L, ldA, ipiv_T, info);
+    if (*info) return;
     // apply pivots to A_R
     LAPACK(dlaswp)(&n2, A_R, ldA, iONE, &n1, ipiv_T, iONE);
 
diff --git a/relapack/src/dsytrf.c b/relapack/src/dsytrf.c
index 43d28f94e..ba869ad11 100644
--- a/relapack/src/dsytrf.c
+++ b/relapack/src/dsytrf.c
@@ -36,7 +36,7 @@ void RELAPACK_dsytrf(
         *info = -2;
     else if (*ldA < MAX(1, *n))
         *info = -4;
-    else if (*lWork < minlWork && *lWork != -1)
+    else if ((*lWork < 1 || *lWork < minlWork) && *lWork != -1)
         *info = -7;
     else if (*lWork == -1) {
         // Work size query
@@ -67,6 +67,7 @@ void RELAPACK_dsytrf(
     blasint nout;
 
     // Recursive kernel
+if (*n != 0)
     RELAPACK_dsytrf_rec(&cleanuplo, n, n, &nout, A, ldA, ipiv, cleanWork, n, info);
 
 #if XSYTRF_ALLOW_MALLOC
diff --git a/relapack/src/dsytrf_rook.c b/relapack/src/dsytrf_rook.c
index 78fa652ab..fcdc2809f 100644
--- a/relapack/src/dsytrf_rook.c
+++ b/relapack/src/dsytrf_rook.c
@@ -36,7 +36,7 @@ void RELAPACK_dsytrf_rook(
         *info = -2;
     else if (*ldA < MAX(1, *n))
         *info = -4;
-    else if (*lWork < minlWork && *lWork != -1)
+    else if ((*lWork <1 || *lWork < minlWork) && *lWork != -1)
         *info = -7;
     else if (*lWork == -1) {
         // Work size query
@@ -56,7 +56,7 @@ void RELAPACK_dsytrf_rook(
 
     if (*info) {
         const blasint minfo = -*info;
-        LAPACK(xerbla)("DSYTRF", &minfo, strlen("DSYTRF"));
+        LAPACK(xerbla)("DSYTRF_ROOK", &minfo, strlen("DSYTRF_ROOK"));
         return;
     }
 
diff --git a/relapack/src/dtrsyl.c b/relapack/src/dtrsyl.c
index 766377300..4948c4977 100644
--- a/relapack/src/dtrsyl.c
+++ b/relapack/src/dtrsyl.c
@@ -49,6 +49,11 @@ void RELAPACK_dtrsyl(
         return;
     }
 
+    if (*m == 0 || *n == 0) {
+        *scale = 1.;
+        return;
+    }
+
     // Clean char * arguments
     const char cleantranA = notransA ? 'N' : (transA ? 'T' : 'C');
     const char cleantranB = notransB ? 'N' : (transB ? 'T' : 'C');
diff --git a/relapack/src/zgetrf.c b/relapack/src/zgetrf.c
index b0d14ffb1..8c3e8a8e8 100644
--- a/relapack/src/zgetrf.c
+++ b/relapack/src/zgetrf.c
@@ -30,6 +30,7 @@ void RELAPACK_zgetrf(
         return;
     }
 
+    if (*m == 0 || *n == 0) return;
     const blasint sn = MIN(*m, *n);
 
     RELAPACK_zgetrf_rec(m, &sn, A, ldA, ipiv, info);
@@ -62,9 +63,11 @@ static void RELAPACK_zgetrf_rec(
     blasint *info
 ) {
 
-    if (*n <= MAX(CROSSOVER_ZGETRF, 1)) {
+    if (*m == 0 || *n == 0) return;
+
+    if ( *n <= MAX(CROSSOVER_ZGETRF, 1)) {
         // Unblocked
-        LAPACK(zgetf2)(m, n, A, ldA, ipiv, info);
+        LAPACK(zgetrf2)(m, n, A, ldA, ipiv, info);
         return;
     }
 
@@ -96,6 +99,8 @@ static void RELAPACK_zgetrf_rec(
 
     // recursion(A_L, ipiv_T)
     RELAPACK_zgetrf_rec(m, &n1, A_L, ldA, ipiv_T, info);
+if (*info) return;
+
     // apply pivots to A_R
     LAPACK(zlaswp)(&n2, A_R, ldA, iONE, &n1, ipiv_T, iONE);
 
diff --git a/relapack/src/zhetrf_rook.c b/relapack/src/zhetrf_rook.c
index 285aea96e..605e3a77f 100644
--- a/relapack/src/zhetrf_rook.c
+++ b/relapack/src/zhetrf_rook.c
@@ -36,7 +36,7 @@ void RELAPACK_zhetrf_rook(
         *info = -2;
     else if (*ldA < MAX(1, *n))
         *info = -4;
-    else if (*lWork < minlWork && *lWork != -1)
+    else if ((*lWork < 1 || *lWork < minlWork) && *lWork != -1)
         *info = -7;
     else if (*lWork == -1) {
         // Work size query
@@ -56,7 +56,7 @@ void RELAPACK_zhetrf_rook(
 
     if (*info) {
         const blasint minfo = -*info;
-        LAPACK(xerbla)("ZHETRF", &minfo, strlen("ZHETRF"));
+        LAPACK(xerbla)("ZHETRF_ROOK", &minfo, strlen("ZHETRF_ROOK"));
         return;
     }
 
diff --git a/relapack/src/zsytrf.c b/relapack/src/zsytrf.c
index f3412ad8f..59daba02f 100644
--- a/relapack/src/zsytrf.c
+++ b/relapack/src/zsytrf.c
@@ -36,7 +36,7 @@ void RELAPACK_zsytrf(
         *info = -2;
     else if (*ldA < MAX(1, *n))
         *info = -4;
-    else if (*lWork < minlWork && *lWork != -1)
+    else if ((*lWork < 1 || *lWork < minlWork) && *lWork != -1)
         *info = -7;
     else if (*lWork == -1) {
         // Work size query
@@ -67,6 +67,7 @@ void RELAPACK_zsytrf(
     blasint nout;
 
     // Recursive kernel
+    if (*n != 0)
     RELAPACK_zsytrf_rec(&cleanuplo, n, n, &nout, A, ldA, ipiv, cleanWork, n, info);
 
 #if XSYTRF_ALLOW_MALLOC
diff --git a/relapack/src/zsytrf_rook.c b/relapack/src/zsytrf_rook.c
index fc6d73645..0fd8e7033 100644
--- a/relapack/src/zsytrf_rook.c
+++ b/relapack/src/zsytrf_rook.c
@@ -36,7 +36,7 @@ void RELAPACK_zsytrf_rook(
         *info = -2;
     else if (*ldA < MAX(1, *n))
         *info = -4;
-    else if (*lWork < minlWork && *lWork != -1)
+    else if ((*lWork < 1 || *lWork < minlWork) && *lWork != -1)
         *info = -7;
     else if (*lWork == -1) {
         // Work size query
@@ -56,7 +56,7 @@ void RELAPACK_zsytrf_rook(
 
     if (*info) {
         const blasint minfo = -*info;
-        LAPACK(xerbla)("ZSYTRF", &minfo, strlen("ZSYTRF"));
+        LAPACK(xerbla)("ZSYTRF_ROOK", &minfo, strlen("ZSYTRF_ROOK"));
         return;
     }
 
@@ -67,6 +67,7 @@ void RELAPACK_zsytrf_rook(
     blasint nout;
 
     // Recursive kernel
+    if (*n != 0)
     RELAPACK_zsytrf_rook_rec(&cleanuplo, n, n, &nout, A, ldA, ipiv, cleanWork, n, info);
 
 #if XSYTRF_ALLOW_MALLOC
diff --git a/relapack/src/ztrsyl.c b/relapack/src/ztrsyl.c
index 567ef115a..9d0107526 100644
--- a/relapack/src/ztrsyl.c
+++ b/relapack/src/ztrsyl.c
@@ -47,6 +47,11 @@ void RELAPACK_ztrsyl(
         return;
     }
 
+    if (*m == 0 || *n == 0) {
+        *scale = 1.;
+        return;
+    }
+
     // Clean char * arguments
     const char cleantranA = notransA ? 'N' : 'C';
     const char cleantranB = notransB ? 'N' : 'C';
diff --git a/relapack/src/ztrtri.c b/relapack/src/ztrtri.c
index 3f6606d84..54854f525 100644
--- a/relapack/src/ztrtri.c
+++ b/relapack/src/ztrtri.c
@@ -69,8 +69,8 @@ static void RELAPACK_ztrtri_rec(
     }
 
     // Constants
-    const double ONE[]  = { 1. };
-    const double MONE[] = { -1. };
+    const double ONE[]  = { 1., 0. };
+    const double MONE[] = { -1. , 0. };
 
     // Splitting
     const blasint n1 = ZREC_SPLIT(*n);